Engine Controls - Tests W/codes - 2.8l Audi A4 B5

ENGINE IDENTIFICATION

Engine can be identified by code stamped on right side of engine block, between cylinder head and power steering pump. (Scheme 1) Serial number is next to engine identification code.

ENGINE IDENTIFICATION CODE

Scheme 1

INTRODUCTION

If no faults were found during preliminary inspection, proceed with self-diagnostics. If no trouble codes or only pass codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).

DIAGNOSTIC TROUBLE CODES (DTCS)

The Powertrain Control Module (PCM) can identify malfunctions and store them in memory in the form of a Diagnostic Trouble Code (DTC). DTCs are stored until memory is erased. If positive battery cable or PCM connector is disconnected, DTCs are erased.

MALFUNCTION INDICATOR LIGHT (MIL)

MIL will illuminate if a failure occurs with Powertrain Control Module (PCM) or Transmission Control Module (TCM).

When ignition is turned on, MIL should come on. When engine is started, MIL should turn off after a couple of seconds. If MIL does not turn off after engine is started, or if MIL comes on while driving, retrieve Diagnostic Trouble Codes (DTCs). See RETRIEVING CODES .

If MIL lights continuously, a malfunction is present that will cause an increase in emissions. If MIL starts to blink, a malfunction is present which may lead to catalytic converter damage. Repair these failures as quickly as possible. For some failures, MIL is only turned on after failure occurs after 2 successive trips with cold engine starts preceding failure.

Some failures will set a DTC which will never cause MIL to light. An example of a failure that could occur and not cause MIL to light would be a FUEL LEVEL TOO LOW signal generated on an A4 model.

HARD FAILURES

Hard failures (also called static malfunctions) cause MIL to come on and a code to set in Powertrain Control Module (PCM) memory. A code that sets as a result of a hard failure will not be erased automatically when the problem is eliminated. These codes must be erased manually.

INTERMITTENT FAILURES

When an intermittent failure occurs, MIL comes on and a Diagnostic Trouble Code (DTC) sets. Powertrain Control Module (PCM) stores DTC as sporadic. Intermittent (sporadic) failures will be erased by PCM if failure does not occur again within 40 engine starts. Intermittent failures may be caused by problems with a sensor, connector or wiring. See INTERMITTENTS in TESTS W/O CODES article.

PCM LOCATION

Powertrain Control Module (PCM) is located in left rear corner of engine compartment inside electronics box.

VISUAL INSPECTION

Prior to retrieving Diagnostic Trouble Codes (DTCs), perform a comprehensive visual inspection of ground connections located on intake manifold, ensure battery negative cable is okay, and check ground cable between engine and vehicle body. Repair as necessary. Check vacuum hoses for breakage and blockage. Check electrical wiring and connectors for damage and corrosion. Repair as necessary.

Note. Manufacturer does not provide procedure for retrieving DTCs without scan tool. If using Volkswagen Audi Group (VAG) 1551 scan tool for diagnosis, follow manufacturer's instructions for operation. VAG 1551 is recommended for diagnosing DTCs.

RETRIEVING CODES

1. Open rear seat ashtray located at rear of center console. Remove cover to access Data Link Connector (DLC). (Scheme 2)
2. Connect VAG 1551 scan tool or generic scan tool to DLC. Turn ignition on or start engine and let it idle. See appropriate table under «DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__diagnostic-trouble-code-dtc-identification).
3. If no communication is possible with PCM, verify connection for scan tool is okay. If scan tool connection is okay, check wiring harness between DLC and PCM for open or short circuit. If wiring harness is okay, PCM is possibly faulty. See «PCM VOLTAGE & GROUND CHECK»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-voltage-ground-check).

Scheme 2

CLEARING CODES

If using VAG 1551 scan tool, follow manufacturers instructions for clearing codes. If using a generic scan tool, turn ignition off. Disconnect positive battery cable or disconnect PCM connector. Codes are now cleared from memory.

PCM VOLTAGE & GROUND CHECK

Note. When Powertrain Control Module (PCM) connectors are disconnected, all Diagnostic Trouble Codes (DTCs) will be erased. It is necessary to use VAG 1598/19 test box and VAG 1527B voltage tester to perform voltage check.

Scheme 3

1. Turn ignition off. Check fuse for PCM. Replace as necessary. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
2. Turn ignition on. Connect VAG 1527B voltage tester to test box socket D10 (B+) and ground (GND). Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check for an open circuit. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Repair as necessary.
3. Connect voltage tester between test box sockets D10 (B+) and ground sockets A19, D3, D7, D12, E3, E7 and E11 in sequence. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check wiring harness for open circuit(s). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Repair as necessary.
4. Connect voltage tester between test box sockets B10 (B+) and engine ground (GND). Voltage tester should light up. If voltage tester lights up, PCM voltage check is good. If voltage tester does not light up, check wiring harness between PCM connector "B", terminal No. 10 and main electrical panel for an open circuit. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) . Repair as necessary.

GROUND CHECK

Turn ignition off. Using a DVOM, check resistance of Powertrain Control Module (PCM) connector "D" terminals No. 3, 7 and 12. Check resistance of PCM connector "E", terminals No. 3, 7 and 11. Resistance on all terminals should be approximately .5 ohms. If resistance is within specification, ground check is good. If resistance is not within specification for any terminal, repair circuit as necessary. See WIRING DIAGRAMS section. Also check ground points on engine for damage or corrosion. Repair as necessary.

PCM CODING

Note. VAG 1551 scan tool is necessary to perform PCM coding.

If Powertrain Control Module (PCM) is replaced it is necessary to code new PCM. If new PCM is not properly coded, the following problems may occur

1. Driveability problems (i.e. harsh shifting).
2. Increased fuel consumption.
3. Increased exhaust emissions.
4. Reduction in transmission life.
5. Malfunctions not present are stored in PCM memory.
6. All PCM functions are not carried out (i.e. EVAP system operation).

Following manufacturers instructions, connect VAG 1551 scan tool to vehicle. Following manufacturers instructions, access PCM coding information using VAG 1551 scan tool. For PCM coding options, see PCM CODING OPTIONS table.

As an example, a properly coded PCM for an A4 model with EGR system, All Wheel Drive (AWD) and Automatic Transmission (A/T) would look like 01251 on the VAG 1551 scan tool.

Note. After coding PCM and starting engine for first time, allow engine to idle for several minutes so PCM can go through a learn function. Idle speed may be erratic while PCM is learning.

PCM CODING OPTIONS

TEST DRIVE

Clear Diagnostic Trouble Codes (DTCs). See CLEARING CODES . Turn ignition off. Start engine. Drive vehicle for at least 10 minutes. Check for any stored DTCs. If DTC sets again, perform testing procedure again. Repair vehicle as necessary.

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION

DTC IDENTIFICATION

CONNECTOR IDENTIFICATION

CONNECTOR IDENTIFICATION DIRECTORY

Scheme 4

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

CIRCUIT TESTS

Note. After any repairs are made, erase DTC memory and test drive vehicle. See CLEARING CODES and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. To properly diagnose vehicle, it is recommended to use VAG 1551 scan tool and VAG 1598/19 test box. (Scheme 3)

DTC P0102/16486 - MAF CIRCUIT LOW INPUT

Note. DTC is set as soon as signal voltage drops to less than .5 volts for longer than .3 seconds with engine speed less than 2000 RPM.

1. Inspect Mass Airflow (MAF) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was okay, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Check MAF sensor fuse. Replace if necessary. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. Using a DVOM, check voltage between MAF sensor connector terminals No. 2 (ground) and 3 (B+). Voltage should be 12-14 volts. If voltage is within specification, go to step 4). If voltage is not within specification, go to next step.
3. Check MAF sensor fuse. Replace if necessary. Check resistance between MAF sensor connector terminal No. 3 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Resistance should be a maximum of .5 ohms. Repair as necessary. Check resistance between MAF sensor connector terminal No. 2 and intake manifold ground. Resistance should be a maximum of .5 ohms. Repair as necessary. Go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between MAF sensor connector terminal No. 1 and test box socket A12. Resistance should be a maximum of one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between MAF sensor connector terminal No. 1 and PCM connector "A" terminal No. 12.
6. With MAF sensor connector connected, slide protective boot back on MAF sensor connector. Turn ignition on. Check voltage between MAF sensor connector terminals No. 2 (ground) and No. 1 (B+). Voltage should be 0.3-1.1 volts. Start engine and let idle. Ensure all electrical accessories are off (including cooling fan).
7. Continuously vary engine speed between idle and 4000 RPM. Voltage should be 1.5 volts minimum to 3.4 volts maximum depending on engine RPM. If voltage readings are not within specification, replace MAF sensor.
8. If vehicle was repaired, clear DTCs and perform test drive. If vehicle was not repaired, PCM is faulty. Replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0103/16487 - MAF CIRCUIT HIGH INPUT

Note. DTC is set as soon as signal voltage rises to more than 5 volts for longer than .5 seconds with engine speed less than 2000 RPM.

1. Inspect Mass Airflow (MAF) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector is okay, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Check MAF sensor fuse. Replace if necessary. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. Using a DVOM, check voltage between MAF sensor connector terminals No. 2 (ground) and 3 (B+). Voltage should be 12-14 volts. If voltage is within specification, go to step 4). If voltage is not within specification, go to next step.
3. Check MAF sensor fuse. Replace if necessary. Check resistance between MAF sensor connector terminal No. 3 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Resistance should be a maximum of .5 ohms. Repair as necessary. Check resistance between MAF sensor connector terminal No. 2 and intake manifold ground. Resistance should be a maximum of .5 ohms. Repair as necessary. Go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between MAF sensor connector terminal No. 1 and test box socket A12. Resistance should be a maximum of one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between MAF sensor connector terminal No. 1 and PCM connector "A" terminal No. 12.
6. With MAF sensor connector connected, slide protective boot back on MAF sensor connector. Turn ignition on. Check voltage between MAF sensor connector terminals No. 2 (ground) and No. 1 (B+). Voltage should be 0.3-1.1 volts. Start engine and let idle. Ensure all electrical accessories are off (including cooling fan).
7. Continuously vary engine speed between idle and 4000 RPM. Voltage should be 1.5 volts minimum to 3.4 volts maximum depending on engine RPM. If voltage readings are not within specification, replace MAF sensor.
8. If vehicle was repaired, clear DTCs and perform test drive. If vehicle was not repaired, PCM is faulty. Replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0116/16500 - ECT SENSOR CKT RANGE/PERFORMANCE PROBLEM

Note. DTC is set as soon as coolant temperature is less than 131°F (55°C) after engine start, but 18 minutes later temperature has not risen to more than 158°F (55°C).

1. Inspect Engine Coolant Temperature (ECT) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect ECT sensor connector. Using a DVOM, check resistance between ECT sensor terminals No. 1 (signal) and 3 (ground). See ECT SENSOR RESISTANCE table. If resistance is to specification, go to next step. If resistance is not to specification, replace ECT sensor. Erase DTC memory and test drive vehicle. ECT SENSOR RESISTANCE Temperature Ohms 68°F (20°C) Approx. 2500 176°F (80°C) Approx. 330
3. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
4. Using DVOM, check resistance between ECT sensor connector terminal No. 3 and engine ground. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 3 and engine ground. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between ECT sensor connector terminal No. 1 and test box socket 16A. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 1 and PCM connector "A" terminal No. 16. Erase DTC memory and test drive vehicle.
6. Check ECT sensor connector terminals No. 1 and 3 for shorting to each other. If circuits are shorting to each other, repair as necessary. Erase DTC memory and test drive vehicle. If circuits are not shorting to each other, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0117/16501 - ECT SENSOR CIRCUIT LOW INPUT

Note. DTC is set as soon as coolant temperature is less than 131°F (55°C) after engine start, but 18 minutes later temperature has not risen to more than 158°F (55°C).

1. Inspect Engine Coolant Temperature (ECT) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect ECT sensor connector. Using a DVOM, check resistance between ECT sensor terminals No. 1 (signal) and 3 (ground). See ECT SENSOR RESISTANCE table. If resistance is to specification, go to next step. If resistance is not to specification, replace ECT sensor. Erase DTC memory and test drive vehicle. ECT SENSOR RESISTANCE Temperature Ohms 68°F (20°C) Approx. 2500 176°F (80°C) Approx. 330
3. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
4. Using DVOM, check resistance between ECT sensor connector terminal No. 3 and engine ground. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 3 and engine ground. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between ECT sensor connector terminal No. 1 and test box socket 16A. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 1 and PCM connector "A" terminal No. 16. Erase DTC memory and test drive vehicle.
6. Check ECT sensor connector terminals No. 1 and 3 for shorting to each other. If circuits are shorting to each other, repair as necessary. Erase DTC memory and test drive vehicle. If circuits are not shorting to each other, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0118/16502 - ECT SENSOR CIRCUIT HIGH INPUT

Note. DTC is set as soon as signal voltage is more than 4.98 volts for more than one second with ignition on (corresponds to coolant temperature of -58°F (-50°C).

1. Inspect Engine Coolant Temperature (ECT) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect ECT sensor connector. Using a DVOM, check resistance between ECT sensor terminals No. 1 (signal) and 3 (ground). See ECT SENSOR RESISTANCE table. If resistance is to specification, go to next step. If resistance is not to specification, replace ECT sensor. Erase DTC memory and test drive vehicle. ECT SENSOR RESISTANCE Temperature Ohms 68°F (20°C) Approx. 2500 176°F (80°C) Approx. 330
3. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
4. Using DVOM, check resistance between ECT sensor connector terminal No. 3 and engine ground. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 3 and engine ground. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between ECT sensor connector terminal No. 1 and test box socket 16A. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 1 and PCM connector "A" terminal No. 16. Erase DTC memory and test drive vehicle.
6. Check ECT sensor connector terminals No. 1 and 3 for shorting to each other. If circuits are shorting to each other, repair as necessary. Erase DTC memory and test drive vehicle. If circuits are not shorting to each other, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0120/16504 - TP SENSOR CIRCUIT MALFUNCTION

Note. DTC is set with idle switch closed as soon as signal voltage of more than .72 volts is seen for longer than 2 seconds (corresponds to a throttle opening of more than 7 degrees).

1. Inspect Throttle Position (TP) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Ensure accelerator pedal cable is properly adjusted. See «ADJUSTMENTS»(/audi/a4/b5-1994-1999/remont/adjustments/#engine-controls-adjustments) article. Remove air intake sound absorber. Disconnect TP sensor connector. Using a DVOM, check continuity between TP sensor terminals No. 4 and 6.
3. Continuity should be present. Open throttle slightly. DVOM should show infinity (no continuity). If continuity readings are not as specified, adjust TP sensor. See CLOSED THROTTLE POSITION (CTP) SWITCH in «ADJUSTMENTS»(/audi/a4/b5-1994-1999/remont/adjustments/#engine-controls-adjustments) article. After adjusting TP sensor, if continuity readings are as specified, go to step 5).
4. If after adjusting TP sensor, continuity readings are not as specified, replace TP sensor. Erase DTC memory and test drive vehicle.
5. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between TP sensor terminal No. 4 (ground) and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Using DVOM, check resistance between TP sensor terminal No. 6 (signal) and test box socket A4. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.

DTC P0121/16505 - TP SENSOR CKT RANGE/PERFORMANCE PROBLEM

Note. DTC is set with coolant temperature more than 158°F (70°C), engine speed 1500-3500 RPM for longer than 2 seconds and engine load more than 68% (from MAF sensor) as soon as TP sensor signal voltage is less than .96 volts (corresponds to a throttle opening less than 12 degrees).

1. Inspect Throttle Position (TP) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Inspect Mass Airflow (MAF) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
3. Turn ignition off. Disconnect TP sensor connector. Using a DVOM, check resistance of TP sensor. See THROTTLE POSITION (TP) SENSOR RESISTANCE table. If resistance readings are not to specification, replace TP sensor. If resistance readings are within specification, go to next step. THROTTLE POSITION (TP) SENSOR RESISTANCE Pin Nos. Ohms: At Idle Ohms: At WOT 1 & 2 1500-2600 N/A 2 & 3 750-1300 (1) 3600 Maximum (1) Resistance should gradually increase as throttle is opened.
4. Turn ignition on. Using a DVOM, check voltage between TP sensor connector terminals No. 1 (B+) and 2 (ground). Check voltage between TP sensor connector terminals No. 1 (B+) and 3 (signal). Voltage should be 4.5-5.5 volts for both tests. If voltage is within specification, erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between TP sensor connector terminal No. 2 and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Using DVOM, check resistance between TP sensor terminal No. 1 and test box socket A3. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
8. Using DVOM, check resistance between TP sensor terminal No. 3 and test box socket A24. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle. If an open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0122/16506 - TP SENSOR CIRCUIT LOW INPUT

Note. DTC is set when signal voltage is less than .1 volt for more than 2 seconds with engine speed more than 6000 RPM.

1. Inspect Throttle Position (TP) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect TP sensor connector. Using a DVOM, check resistance of TP sensor. See THROTTLE POSITION (TP) SENSOR RESISTANCE table. If resistance readings are not to specification, replace TP sensor. If resistance readings are within specification, go to next step. THROTTLE POSITION (TP) SENSOR RESISTANCE Pin Nos. Ohms: At Idle Ohms: At WOT 1 & 2 1500-2600 N/A 2 & 3 750-1300 (1) 3600 Maximum (1) Resistance should gradually increase as throttle is opened.
3. Turn ignition on. Using a DVOM, check voltage between TP sensor connector terminals No. 1 (B+) and 2 (ground). Check voltage between TP sensor connector terminals No. 1 (B+) and 3 (signal). Voltage should be 4.5-5.5 volts for both tests. If voltage is within specification, erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between TP sensor connector terminal No. 2 and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Using DVOM, check resistance between TP sensor terminal No. 1 and test box socket A3. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Using DVOM, check resistance between TP sensor terminal No. 3 and test box socket A24. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle. If an open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0123/16507 - TP SENSOR CIRCUIT HIGH INPUT

Note. DTC is set when signal voltage is more than 4.9 volts for more than 2 seconds.

1. Inspect Throttle Position (TP) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect TP sensor connector. Using a DVOM, check resistance of TP sensor. See THROTTLE POSITION (TP) SENSOR RESISTANCE table. If resistance readings are not to specification, replace TP sensor. If resistance readings are within specification, go to next step. THROTTLE POSITION (TP) SENSOR RESISTANCE Pin Nos. Ohms: At Idle Ohms: At WOT 1 & 2 1500-2600 N/A 2 & 3 750-1300 (1) 3600 Maximum (1) Resistance should gradually increase as throttle is opened.
3. Turn ignition on. Using a DVOM, check voltage between TP sensor connector terminals No. 1 (B+) and 2 (ground). Check voltage between TP sensor connector terminals No. 1 (B+) and 3 (signal). Voltage should be 4.5-5.5 volts for both tests. If voltage is within specification, erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between TP sensor connector terminal No. 2 and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Using DVOM, check resistance between TP sensor terminal No. 1 and test box socket A3. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Using DVOM, check resistance between TP sensor terminal No. 3 and test box socket A24. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle. If an open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0130/16514 - HO2S CIRCUIT MALFUNCTION (BANK 1, SENSOR 1)

Note. DTC is set when difference between minimum and maximum signal voltage is less than 500 mV with coolant temperature more than 176°F (80°C) 60 seconds after start of mixture control.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle. See «CLEARING CODES»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__clearing-codes) and TEST DRIVE in this article.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. See «CLEARING CODES»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__clearing-codes) and TEST DRIVE in this article. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A20. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «CLEARING CODES»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__clearing-codes) and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article.

DTC P0132/16516 - HO2S CIRCUIT HIGH VOLTAGE (BANK 1, SENSOR 1)

Note. DTC is set when difference more than 1.4 volts for more than 5 seconds, 123 seconds after engine start.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A20. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0133/16517 - HO2S CKT SLOW RESPONSE (BANK 1, SENSOR 1)

Note. DTC is set when flank rise time (limit value 90 milliseconds) and/or flank drop time (limit value 100 milliseconds) of probe signal has been exceeded between 300-500 mV.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Replace HO2S. Torque HO2S to 37 ft. lbs. (50 N.m). Erase DTC memory and test drive vehicle, If code sets again, go to next step.
3. If malfunction has occurred again within a short time after replacing HO2S, check for poor fuel quality. Poor fuel quality can cause this code. Remove old fuel from tank. Fill tank with premium unleaded fuel.
4. Erase DTC memory and test drive vehicle.

DTC P0134/16518 - HO2S CIRCUIT NO ACTIVITY DETECTED (BANK 1, SENSOR 1)

Note. DTC is set when signal voltage is 370-430 mV for more than 4 seconds, 123 seconds after engine start with coolant temperature more than 86°F (30°C).

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A20. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0135/16519 - HO2S HEATER CIRCUIT MALFUNCTION (BANK 1, SENSOR 1)

Note. HO2S heater before 3-way catalytic converter is switched on by fuel pump relay. DTC is set after engine start with battery voltage 9-16 volts and heating current 280-540 mV for more than one second (battery voltage fluctuations).

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Black 4-pin connector located in right rear corner of engine compartment. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 2 and PCM connector terminal E10. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If DTC sets again, perform testing procedure again. If resistance is not within specification, replace HO2S. Erase DTC memory and test drive vehicle.

DTC P0136/16520 - HO2S CKT MALFUNCTION (BANK 1, SENSOR 2)

Note. DTC is set 123 seconds after engine start when signal voltage during a deceleration fuel shut-off is more than 300 mV with coolant temperature more than 176°F (80°C) and 45 seconds after probe heating, after 3-way catalytic converter is switched on. Length of fuel shut-off deceleration must be longer than 4 seconds.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminals No. 3 (ground) and 4 (signal). If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 3 (ground) and 4 (signal). Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 3 and test box socket C17. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket C20. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
7. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0138/16522 - HO2S CKT HIGH VOLTAGE (BANK 1, SENSOR 2)

Note. DTC is set 3 minutes after engine start when HO2S voltage is more than 1.4 volts for more than 5 seconds.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminals No. 3 (ground) and 4 (signal). If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 3 (ground) and 4 (signal). Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 3 and test box socket C17. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket C20. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
7. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0141/16525 - HO2S HEATER CIRCUIT MALFUNCTION (BANK 1, SENSOR 2)

Note. HO2S heater behind 3-way catalytic converter is not switched on at engine start. Heater is switched on when calculated exhaust gas temperature is less than 586°F (308°C).

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Green 4-pin connector located in right rear corner of engine compartment. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between PCM connector "E" terminals No. 2 and 8. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If resistance is not within specification, replace HO2S. Erase DTC memory and test drive vehicle.

DTC P0150/16534 - HO2S CKT MALFUNCTION (BANK 2, SENSOR 1)

Note. DTC is set when difference between minimum and maximum signal voltage is less than 500 mV with coolant temperature more than 176°F (80°C) 60 seconds after start of mixture control.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A21. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
6. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0152/16536 - HO2S CKT HIGH VOLTAGE (BANK 2, SENSOR 1)

Note. DTC is set 123 seconds after engine start when HO2S voltage is more than 1.4 volts for more than 5 seconds.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A21. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
6. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0153/16537 - HO2S CKT SLOW RESPONSE (BANK 2, SENSOR 1)

Note. DTC is set when flank rise time (limit value 90 milliseconds) and/or flank drop time (limit value 100 milliseconds) of probe signal has been exceeded between 300-500 mV.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Replace HO2S. Torque HO2S to 37 ft. lbs. (50 N.m). Erase DTC memory and test drive vehicle. If DTC sets again, go to next step.
3. If malfunction has occurred again within a short time after replacing HO2S, check for poor fuel quality. Poor fuel quality can cause this code. Remove old fuel from tank. Fill tank with premium unleaded fuel.
4. Erase DTC memory and test drive vehicle.

DTC P0154/16538 - HO2S CIRCUIT NO ACTIVITY DETECTED (BANK 2, SENSOR 1)

Note. DTC is set when signal voltage is 370-430 mV for more than 4 seconds, 123 seconds after engine start with coolant temperature more than 86°F (30°C).

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A21. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0155/16539 - HO2S HEATER CIRCUIT MALFUNCTION (BANK 2, SENSOR 1)

Note. HO2S heater before 3-way catalytic converter is switched on by fuel pump relay.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Black 4-pin connector located near HO2S. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 2 and PCM connector terminal E9. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If resistance is not within specification, replace HO2S. Erase DTC memory and test drive vehicle.

DTC P0156/16540 - HO2S CKT MALFUNCTION (BANK 2, SENSOR 2)

Note. DTC is set 123 seconds after engine start with coolant temperature more than 176°F (80°C) and 45 seconds after HO2S heater behind 3-way catalytic converter is switched on when signal voltage during deceleration fuel shut-off is more than 300 mV. Length of deceleration fuel shut-off must be longer than 4 seconds.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 3 and test box socket C17. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket C21. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. If an open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0158/16542 - HO2S CKT HIGH VOLTAGE (BANK 2, SENSOR 2)

Note. DTC is set 3 minutes after engine start when HO2S voltage is more than 1.4 volts for more than 5 seconds.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 3 and test box socket C17. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket C21. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. If an open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0161/16545 - HO2S HEATER CIRCUIT MALFUNCTION (BANK 2, SENSOR 2)

Note. HO2S heater behind 3-way catalytic converter is not switched on at engine start. Heater is switched on when calculated exhaust gas temperature is less than 586°F (308°).

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Brown 4-pin connector located in right rear corner of engine compartment. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between PCM connector "E" terminals No. 2 and 3. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If resistance is not within specification, replace HO2S.

DTC P0170/16554 - FUEL TRIM MALFUNCTION (BANK 1)

Note. DTC is set when PCM learning procedure difference between a newly learned HO2S learning value and optional stored HO2S learning value is more than plus or minus 8 percent.

1. Bank 1 identifies fuel injectors on passenger side of engine. Inspect intake manifold area for leaks. Repair as necessary. If a leak was not found, go to next step. If a leak was repaired, erase DTC memory and test drive vehicle.
2. Inspect engine oil for fuel contamination. Engine oil contamination can be caused by frequent cold starts or short trips. Change engine oil if necessary. If engine oil is okay, go to next step. If engine oil was changed, erase DTC memory and test drive vehicle.
3. Check MAF sensor fuse. Replace if necessary. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. Using a DVOM, check voltage between MAF sensor connector terminals No. 2 (ground) and 3 (B+). Voltage should be 12-14 volts. If voltage is within specification, go to step 5). If voltage is not within specification, go to next step.
4. Check MAF sensor fuse. Replace if necessary. Check resistance between MAF sensor connector terminal No. 3 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Resistance should be a maximum of .5 ohms. Repair as necessary. Check resistance between MAF sensor connector terminal No. 2 and intake manifold ground. Resistance should be a maximum of .5 ohms. Repair as necessary. Go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between MAF sensor connector terminal No. 1 and test box socket A12. Resistance should be a maximum of one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between MAF sensor connector terminal No. 1 and PCM connector "A" terminal No. 12.
7. With MAF sensor connector connected, slide protective boot back on MAF sensor connector. Turn ignition on. Check voltage between MAF sensor connector terminals No. 2 (ground) and No. 1 (B+). Voltage should be 0.3-1.1 volts. Start engine and let idle. Ensure all electrical accessories are off (including cooling fan).
8. Continuously vary engine speed between idle and 4000 RPM. Voltage should be 1.5 volts minimum to 3.4 volts maximum depending on engine RPM. If voltage readings are within specification, MAF sensor is okay. Go to next step. If voltage readings are not within specification, replace MAF sensor. Erase DTC memory and test drive vehicle.
9. Check engine for oil burning. Test engine compression pressure. See COMPRESSION SPECIFICATIONS table. Repair engine as necessary. Erase DTC memory and test drive vehicle.

COMPRESSION SPECIFICATIONS

DTC P0171/16555 - SYSTEM TOO LEAN (BANK 1)

Note. DTC is set when HO2S control has exceeded the learning limit in rich direction, but HO2S still recognizes mixture is too lean.

1. Bank 1 identifies fuel injectors on passenger side of engine. If DTC P0174/16558 SYSTEM TOO LEAN (BANK 2) is also set in memory, this indicates a condition is present causing both cylinder banks to run too lean. Go to step 7). If DTC P0174/16558 is not also set in memory, go to next step.
2. Inspect exhaust system on passenger side of vehicle for a leak. Repair as necessary. If an exhaust leak was not found, go to next step. If an exhaust leak was repaired, erase DTC memory and test drive vehicle.
3. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
4. Inspect spark plugs and ignition cables for malfunction on passenger side of engine. If a malfunction was not repaired, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle.
5. Inspect fuel injectors on passenger side of vehicle for poor electrical connection or dirty/clogged injectors. See FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. If a malfunction was not repaired, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle.
6. Inspect intake valves for carbon deposits. Clean as necessary. If intake valves did not have carbon deposits, go to next step. If intake valves had carbon deposits, erase DTC memory and test drive vehicle.
7. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle.
8. Inspect air intake system for a large leak. Repair as necessary. If a large intake leak was not found, go to next step. If a large intake leak was repaired, erase DTC memory and test drive vehicle.
9. DTC may have been set because of low fuel pressure. Inspect fuel lines for leaks. Inspect vacuum line to fuel pressure regulator. Inspect fuel pressure regulator. Inspect fuel filter. Inspect fuel pump. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
10. Disconnect EVAP canister purge valve electrical connector. Using DVOM, check EVAP canister purge valve resistance. Measure resistance across EVAP canister purge valve terminals. Resistance should be 20-28 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace EVAP canister purge valve. Erase DTC memory and test drive vehicle.
11. With ignition on, connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for EVAP canister purge valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
12. Using a DVOM, check wiring between EVAP canister purge valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
13. Connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EVAP canister purge valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, ensure EVAP canister purge valve is not mechanically binding. Replace as necessary. Erase DTC memory and test drive vehicle.
14. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
15. If voltage tester had lit up constantly, go to step 18). If voltage tester did not flash, using DVOM, check resistance between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 17).
16. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
17. Using DVOM, check for short to B+ between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
18. Using DVOM, check for a short to ground between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.

DTC P0172/16556 - SYSTEM TOO RICH (BANK 1)

Note. DTC is set when HO2S control has dropped below learning limit in lean direction, but HO2S still recognizes mixture is too rich.

1. Bank 1 identifies fuel injectors on passenger side of engine. If DTC P0175/16559 SYSTEM TOO RICH (BANK 2) is also set in memory, this indicates that fuel pressure is too high. Test fuel pressure and residual fuel pressure. Refer to FUEL PRESSURE TEST in the «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. If fuel pressure is okay, go to next step. If fuel pressure was repaired, erase DTC memory and test drive vehicle.
2. Inspect fuel injectors on passenger side of vehicle for poor electrical connection or dirty/clogged injectors. See FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P0173/16557 - FUEL TRIM MALFUNCTION (BANK 2)

Note. DTC is set when PCM learning procedure difference between a newly learned HO2S learning value and optional stored HO2S learning value is more than plus or minus 8 percent.

1. Bank 2 identifies fuel injectors on driver side of engine. Inspect intake manifold area for leaks. Repair as necessary. If a leak was not found, go to next step. If a leak was repaired, erase DTC memory and test drive vehicle.
2. Inspect engine oil for fuel contamination. Engine oil contamination can be caused by frequent cold starts or short trips. Change engine oil if necessary. If engine oil is okay, go to next step. If engine oil was changed, erase DTC memory and test drive vehicle.
3. Check MAF sensor fuse. Replace if necessary. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. Using a DVOM, check voltage between MAF sensor connector terminals No. 2 (ground) and 3 (B+). Voltage should be 12-14 volts. If voltage is within specification, go to step 5). If voltage is not within specification, go to next step.
4. Check MAF sensor fuse. Replace if necessary. Check resistance between MAF sensor connector terminal No. 3 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Resistance should be a maximum of .5 ohms. Repair as necessary. Check resistance between MAF sensor connector terminal No. 2 and intake manifold ground. Resistance should be a maximum of .5 ohms. Repair as necessary. Go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between MAF sensor connector terminal No. 1 and test box socket A12. Resistance should be a maximum of one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between MAF sensor connector terminal No. 1 and PCM connector "A" terminal No. 12.
7. With MAF sensor connector connected, slide protective boot back on MAF sensor connector. Turn ignition on. Check voltage between MAF sensor connector terminals No. 2 (ground) and No. 1 (B+). Voltage should be 0.3-1.1 volts. Start engine and let idle. Ensure all electrical accessories are off (including cooling fan).
8. Continuously vary engine speed between idle and 4000 RPM. Voltage should be 1.5 volts minimum to 3.4 volts maximum depending on engine RPM. If voltage readings are within specification, MAF sensor is okay. Go to next step. If voltage readings are not within specification, replace MAF sensor. Erase DTC memory and test drive vehicle.
9. Check engine for oil burning. Test engine compression pressure. See COMPRESSION SPECIFICATIONS table. Repair engine as necessary. Erase DTC memory and test drive vehicle.

COMPRESSION SPECIFICATIONS

DTC P0174/16558 - SYSTEM TOO LEAN (BANK 2)

Note. DTC is set when HO2S control has exceeded the learning limit in rich direction, but HO2S still recognizes mixture is too lean.

1. Bank 1 identifies fuel injectors on passenger side of engine. If DTC P0171/16555 SYSTEM TOO LEAN (BANK 1) is also set in memory, this indicates a condition is present causing both cylinder banks to run too lean. Go to step 7). If DTC P0171/16555 is not also set in memory, go to next step.
2. Inspect exhaust system on driver side of vehicle for a leak. Repair as necessary. If an exhaust leak was not found, go to next step. If an exhaust leak was repaired, erase DTC memory and test drive vehicle.
3. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
4. Inspect spark plugs and ignition cables for malfunction on driver side of vehicle. If a malfunction was not repaired, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle.
5. Inspect fuel injectors on driver side of vehicle for poor electrical connection or dirty/clogged injectors. See FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. If a malfunction was not repaired, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle.
6. Inspect intake valves for carbon deposits. Clean as necessary. If intake valves did not have carbon deposits, continue troubleshooting other DTCs. See «DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__diagnostic-trouble-code-dtc-identification) table. If intake valves had carbon deposits, erase DTC memory and test drive vehicle.
7. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 12.7 qts. (12 L) of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle.
8. Inspect air intake system for a large leak. Repair as necessary. If a large intake leak was not found, go to next step. If a large intake leak was repaired, erase DTC memory and test drive vehicle.
9. DTC may have been set because of low fuel pressure. Inspect fuel lines for leaks. Inspect vacuum line to fuel pressure regulator. Inspect fuel pressure regulator. Inspect fuel filter. Inspect fuel pump. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
10. Disconnect EVAP canister purge valve electrical connector. Using DVOM, check EVAP canister purge valve resistance. Measure resistance across EVAP canister purge valve terminals. Resistance should be 20-28 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace EVAP canister purge valve. Erase DTC memory and test drive vehicle.
11. With ignition on, connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminal No. 1 and ground. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for EVAP canister purge valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
12. Using a DVOM, check wiring between EVAP canister purge valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
13. Connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EVAP canister purge valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, ensure EVAP canister purge valve is not mechanically binding. Replace as necessary. Erase DTC memory and test drive vehicle.
14. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
15. If voltage tester had lit up constantly, go to step 18). If voltage tester did not flash, using DVOM, check resistance between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 17).
16. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
17. Using DVOM, check for short to B+ between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
18. Using DVOM, check for a short to ground between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. Refer to «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.

DTC P0175/16559 - SYSTEM TOO RICH (BANK 2)

Note. DTC is set when HO2S control has dropped below learning limit in lean direction, but HO2S still recognizes mixture is too rich.

1. Bank 2 identifies fuel injectors on driver side of engine. If DTC P0172/16556 SYSTEM TOO RICH (BANK 1) is also set in memory, this indicates that fuel pressure is too high. Test fuel pressure and residual fuel pressure. See FUEL PRESSURE TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. If fuel pressure is okay, go to next step. If fuel pressure was repaired, erase DTC memory and test drive vehicle.
2. Inspect fuel injectors on driver side of vehicle for poor electrical connection or dirty/clogged injectors. See FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P0300/16684 - RANDOM MISFIRE DETECTED

Note. DTC is set when misfiring has been recognized in more than one cylinder. If misfiring rate is low, MIL is lit after 2 successive trips without a preceding cold start with a malfunction occurring. If misfiring rate is high, MIL will immediately start blinking. Damage to 3-way catalyst is possible. Repair malfunction as soon as possible.

1. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle. If DTC P1250/17658 FUEL LEVEL TOO LOW is not set in memory, go to next step.
2. If other DTCs are stored, (i.e. fuel injector, HO2S, fuel system, etc.) these stored DTCs may cause misfire. Repair other DTCs as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. If misfiring has been recognized for several or all cylinders, go to step 5). If misfiring has been recognized on 2 cylinders (i.e., 2 and 4, 3 and 5, 1 and 6), go to next step. If misfiring has only been recognized on one cylinder (i.e. 2 or 4, 3 or 5, 1 or 6), check ignition wiring harness, spark plug cables and fuel injectors for cylinder(s) which are faulty. For fuel injector testing, see FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. Inspect ignition coil for affected cylinders. See IGNITION COIL in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. If vehicle was not repaired, go to next step. If vehicle was repaired, erase DTC memory and test drive vehicle.
5. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
6. Inspect fuel pump and residual fuel pressure. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
7. Check EGR valve and system components. EGR flow may be too high. Inspect hoses, etc. Repair as necessary. If EGR system is okay, go to next step. If EGR system was repaired, erase DTC memory and test drive vehicle.
8. Inspect fuel injectors for carbon deposits. Replace as necessary. If fuel injectors are okay, go to next step. If fuel injectors were replaced, erase DTC memory and test drive vehicle.
9. Inspect intake valves for carbon deposits. Clean as necessary. Erase DTC memory and test drive vehicle.

DTC P0301/16685 - CYLINDER NO. 1 MISFIRE DETECTED

Note. If misfiring rate is low, MIL is lit after 2 successive trips without a preceding cold start with a malfunction occurring. If misfiring rate is high, MIL will immediately start blinking. Damage to 3-way catalyst is possible. Repair malfunction as soon as possible.

1. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle. If DTC P1250/17658 FUEL LEVEL TOO LOW is not set in memory, go to next step.
2. If other DTCs are stored, (i.e. fuel injector, HO2S, fuel system, etc.) these stored DTCs may cause misfire. Repair other DTCs as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. If misfiring has been recognized for several or all cylinders, go to step 5). If misfiring has been recognized on 2 cylinders (i.e., 2 and 4, 3 and 5, 1 and 6), go to next step. If misfiring has only been recognized on one cylinder (i.e. 2 or 4, 3 or 5, 1 or 6), check ignition wiring harness, spark plug cables and fuel injectors for cylinder(s) which are faulty. For fuel injector testing, see FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. Inspect ignition coil for affected cylinders. See IGNITION COIL in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. If vehicle was not repaired, go to next step. If vehicle was repaired, erase DTC memory and test drive vehicle.
5. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
6. Inspect fuel pump and residual fuel pressure. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
7. Check EGR valve and system components. EGR flow may be too high. Inspect hoses, etc. Repair as necessary. If EGR system is okay, go to next step. If EGR system was repaired, erase DTC memory and test drive vehicle.
8. Inspect fuel injectors for carbon deposits. Replace as necessary. If fuel injectors are okay, go to next step. If fuel injectors were replaced, erase DTC memory and test drive vehicle.
9. Inspect intake valves for carbon deposits. Clean as necessary. Erase DTC memory and test drive vehicle.

DTC P0302/16686 - CYLINDER NO. 2 MISFIRE DETECTED

Note. If misfiring rate is low, MIL is lit after 2 successive trips without a preceding cold start with a malfunction occurring. If misfiring rate is high, MIL will immediately start blinking. Damage to 3-way catalyst is possible. Repair malfunction as soon as possible.

1. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle. If DTC P1250/17658 FUEL LEVEL TOO LOW is not set in memory, go to next step.
2. If other DTCs are stored, (i.e. fuel injector, HO2S, fuel system, etc.) these stored DTCs may cause misfire. Repair other DTCs as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. If misfiring has been recognized for several or all cylinders, go to step 5). If misfiring has been recognized on 2 cylinders (i.e., 2 and 4, 3 and 5, 1 and 6), go to next step. If misfiring has only been recognized on one cylinder (i.e. 2 or 4, 3 or 5, 1 or 6), check ignition wiring harness, spark plug cables and fuel injectors for cylinder(s) which are faulty. For fuel injector testing, see FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle.
4. Inspect ignition coil for affected cylinders. See IGNITION COIL in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. If vehicle was not repaired, go to next step. If vehicle was repaired, erase DTC memory and test drive vehicle.
5. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
6. Inspect fuel pump and residual fuel pressure. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
7. Check EGR valve and system components. EGR flow may be too high. Inspect hoses, etc. Repair as necessary. If EGR system is okay, go to next step. If EGR system was repaired, erase DTC memory and test drive vehicle.
8. Inspect fuel injectors for carbon deposits. Replace as necessary. If fuel injectors are okay, go to next step. If fuel injectors were replaced, erase DTC memory and test drive vehicle.
9. Inspect intake valves for carbon deposits. Clean as necessary. Erase DTC memory and test drive vehicle.

DTC P0303/16687 - CYLINDER NO. 3 MISFIRE DETECTED

Note. If misfiring rate is low, MIL is lit after 2 successive trips without a preceding cold start with a malfunction occurring. If misfiring rate is high, MIL will immediately start blinking. Damage to 3-way catalyst is possible. Repair malfunction as soon as possible.

1. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle. If DTC P1250/17658 FUEL LEVEL TOO LOW is not set in memory, go to next step.
2. If other DTCs are stored, (i.e. fuel injector, HO2S, fuel system, etc.) these stored DTCs may cause misfire. Repair other DTCs as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. If misfiring has been recognized for several or all cylinders, go to step 5). If misfiring has been recognized on 2 cylinders (i.e., 2 and 4, 3 and 5, 1 and 6), go to next step. If misfiring has only been recognized on one cylinder (i.e. 2 or 4, 3 or 5, 1 or 6), check ignition wiring harness, spark plug cables and fuel injectors for cylinder(s) which are faulty. For fuel injector testing, see FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. Inspect ignition coil for affected cylinders. See IGNITION COIL in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. If vehicle was not repaired, go to next step. If vehicle was repaired, erase DTC memory and test drive vehicle.
5. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
6. Inspect fuel pump and residual fuel pressure. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
7. Check EGR valve and system components. EGR flow may be too high. Inspect hoses, etc. Repair as necessary. If EGR system is okay, go to next step. If EGR system was repaired, erase DTC memory and test drive vehicle.
8. Inspect fuel injectors for carbon deposits. Replace as necessary. If fuel injectors are okay, go to next step. If fuel injectors were replaced, erase DTC memory and test drive vehicle.
9. Inspect intake valves for carbon deposits. Clean as necessary. Erase DTC memory and test drive vehicle.

DTC P0304/16688 - CYLINDER NO. 4 MISFIRE DETECTED

Note. If misfiring rate is low, MIL is lit after 2 successive trips without a preceding cold start with a malfunction occurring. If misfiring rate is high, MIL will immediately start blinking. Damage to 3-way catalyst is possible. Repair malfunction as soon as possible.

1. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle. If DTC P1250/17658 FUEL LEVEL TOO LOW is not set in memory, go to next step.
2. If other DTCs are stored, (i.e. fuel injector, HO2S, fuel system, etc.) these stored DTCs may cause misfire. Repair other DTCs as necessary. Erase DTC memory and test drive vehicle.
3. If misfiring has been recognized for several or all cylinders, go to step 5). If misfiring has been recognized on 2 cylinders (i.e., 2 and 4, 3 and 5, 1 and 6), go to next step. If misfiring has only been recognized on one cylinder (i.e. 2 or 4, 3 or 5, 1 or 6), check ignition wiring harness, spark plug cables and fuel injectors for cylinder(s) which are faulty. For fuel injector testing, see FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. Inspect ignition coil for affected cylinders. See IGNITION COIL in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. If vehicle was not repaired, go to next step. If vehicle was repaired, erase DTC memory and test drive vehicle.
5. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
6. Inspect fuel pump and residual fuel pressure. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
7. Check EGR valve and system components. EGR flow may be too high. Inspect hoses, etc. Repair as necessary. If EGR system is okay, go to next step. If EGR system was repaired, erase DTC memory and test drive vehicle.
8. Inspect fuel injectors for carbon deposits. Replace as necessary. If fuel injectors are okay, go to next step. If fuel injectors were replaced, erase DTC memory and test drive vehicle.
9. Inspect intake valves for carbon deposits. Clean as necessary. Erase DTC memory and test drive vehicle.

DTC P0305/16689 - CYLINDER NO. 5 MISFIRE DETECTED

Note. If misfiring rate is low, MIL is lit after 2 successive trips without a preceding cold start with a malfunction occurring. If misfiring rate is high, MIL will immediately start blinking. Damage to 3-way catalyst is possible. Repair malfunction as soon as possible.

1. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle. If DTC P1250/17658 FUEL LEVEL TOO LOW is not set in memory, go to next step.
2. If other DTCs are stored, (i.e. fuel injector, HO2S, fuel system, etc.) these stored DTCs may cause misfire. Repair other DTCs as necessary. Erase DTC from memory and test drive vehicle.
3. If misfiring has been recognized for several or all cylinders, go to step 5). If misfiring has been recognized on 2 cylinders (i.e., 2 and 4, 3 and 5, 1 and 6), go to next step. If misfiring has only been recognized on one cylinder (i.e. 2 or 4, 3 or 5, 1 or 6), check ignition wiring harness, spark plug cables and fuel injectors for cylinder(s) which are faulty. For fuel injector testing, see FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. Inspect ignition coil for affected cylinders. See IGNITION COIL in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. If vehicle was not repaired, go to next step. If vehicle was repaired, erase DTC memory and test drive vehicle.
5. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
6. Inspect fuel pump and residual fuel pressure. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
7. Check EGR valve and system components. EGR flow may be too high. Inspect hoses, etc. Repair as necessary. If EGR system is okay, go to next step. If EGR system was repaired, erase DTC memory and test drive vehicle.
8. Inspect fuel injectors for carbon deposits. Replace as necessary. If fuel injectors are okay, go to next step. If fuel injectors were replaced, erase DTC memory and test drive vehicle.
9. Inspect intake valves for carbon deposits. Clean as necessary. Erase DTC memory and test drive vehicle.

DTC P0306/16690 - CYLINDER NO. 6 MISFIRE DETECTED

Note. If misfiring rate is low, MIL is lit after 2 successive trips without a preceding cold start with a malfunction occurring. If misfiring rate is high, MIL will immediately start blinking. Damage to 3-way catalyst is possible. Repair malfunction as soon as possible.

1. If DTC P1250/17658 FUEL LEVEL TOO LOW is also set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. If fuel level is okay, go to next step. If fuel level was low, erase DTC memory and test drive vehicle. If DTC P1250/17658 FUEL LEVEL TOO LOW is not set in memory, go to next step.
2. If other DTCs are stored, (i.e. fuel injector, HO2S, fuel system, etc.) these stored DTCs may cause misfire. Repair other DTCs as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. If misfiring has been recognized for several or all cylinders, go to step 5). If misfiring has been recognized on 2 cylinders (i.e., 2 and 4, 3 and 5, 1 and 6), go to next step. If misfiring has only been recognized on one cylinder (i.e. 2 or 4, 3 or 5, 1 or 6), check ignition wiring harness, spark plug cables and fuel injectors for cylinder(s) which are faulty. For fuel injector testing, see FUEL INJECTOR TEST in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. Inspect ignition coil for affected cylinders. See IGNITION COIL in «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Repair as necessary. If vehicle was not repaired, go to next step. If vehicle was repaired, erase DTC memory and test drive vehicle.
5. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
6. Inspect fuel pump and residual fuel pressure. See FUEL PUMP table. Repair as necessary. If components are okay, go to next step. If a malfunction was repaired, erase DTC memory and test drive vehicle. FUEL PUMP PERFORMANCE Function Specification System Pressure With Engine Idling (1) 55-61 psi (3.8-4.2 bar) With Engine Idling (Warm) (2) 46-55 (3.2-3.8 bar) Residual Pressure Engine Cold (3) 32 psi (2.2 bar) Engine Hot (3) 44 psi (3.0 bar) Fuel Injector/Injection Rate (4) 2.9-3.7 oz. (86-109 ml) (1) With fuel pressure regulator vacuum hose disconnected. (2) With fuel pressure regulator vacuum hose connected. (3) After 10 minutes. (4) Per 30 seconds of operation.
7. Check EGR valve and system components. EGR flow may be too high. Inspect hoses, etc. Repair as necessary. If EGR system is okay, go to next step. If EGR system was repaired, erase DTC memory and test drive vehicle.
8. Inspect fuel injectors for carbon deposits. Replace as necessary. If fuel injectors are okay, go to next step. If fuel injectors were replaced, erase DTC memory and test drive vehicle.
9. Inspect intake valves for carbon deposits. Clean as necessary. Erase DTC memory and test drive vehicle.

DTC P0322/16706 - IGNITION ENGINE SPEED INPUT CIRCUIT NO SIGNAL

Note. DTC is set during engine start when no ignition or fuel injection occurs.

1. If DTC P1339/17747 CRANKSHAFT POSITION SENSOR/ENGINE SPEED SENSOR CROSS CONNECTED is also set in memory, this indicates connectors for Crankshaft Position (CKP) sensor and engine speed sensor are cross connected. Disconnect connectors and connect to correct sensor. Erase DTC memory and test drive vehicle. If DTC P1339/17747 CRANKSHAFT POSITION SENSOR/ENGINE SPEED SENSOR CROSS CONNECTED is not set in memory, go to next step.
2. Inspect engine speed sensor connector for looseness and/or corrosion. Engine speed sensor is located on driver side, rear of engine. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
3. Inspect engine speed sensor for incorrect adjustment. See ENGINE SPEED (RPM) SENSOR BRACKET in «ADJUSTMENTS»(/audi/a4/b5-1994-1999/remont/adjustments/#engine-controls-adjustments) article. Adjust sensor if necessary. If sensor was not adjusted, go to next step. If sensor was adjusted, erase DTC memory and test drive vehicle.
4. Remove and inspect engine speed sensor for metal chips (contamination). If no contamination was found, go to next step. If contamination was found, clean as necessary. Erase DTC memory and test drive vehicle.
5. Disconnect Gray 3-pin engine speed sensor connector. Using a DVOM, check resistance between engine speed sensor connector (sensor side) terminals No. 1 and 2. Resistance should be approximately one ohm. If resistance is to specification, go to next step. If resistance is not to specification, replace engine speed sensor. Erase DTC memory and test drive vehicle.
6. Connect DVOM between engine speed sensor connector (sensor side) terminals No. 1 and 3, then 2 and 3. Resistance should be infinite (open). If resistance is to specification, go to next step. If resistance is not to specification, replace engine speed sensor. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between engine speed sensor connector (harness side) terminal No. 3 and ground. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair short circuit to ground. Erase DTC memory and test drive vehicle. If a short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
9. Using DVOM, check resistance between engine speed sensor connector (harness side) terminal No. 1 and test box socket A11. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair short circuit to ground. Erase DTC memory and test drive vehicle. If short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
10. Using DVOM, check resistance between engine speed sensor connector (harness side) terminal No. 2 and test box socket A9. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair short circuit to ground. Erase DTC memory and test drive vehicle. If short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P0327/16711 - KNOCK SENSOR NO. 1 CIRCUIT LOW INPUT (BANK 1 OR SINGLE SENSOR)

Note. DTC is set if knock sensor output voltage is less than .2 volts, coolant temperature more than 68°F (20°C), engine speed more than 3500 RPM and engine load more than 16 percent. Ignition timing will be retarded 12° according to ignition map in PCM.

1. If DTC P0332/16716 KNOCK SENSOR NO. 2 CIRCUIT LOW INPUT (BANK 2) is also set in memory, perform test steps 2)-8), then continue and perform test steps 9)-15). If DTC P0332/16716 KNOCK SENSOR NO. 2 CIRCUIT LOW INPUT (BANK 2) is not also set in memory, perform test steps 2)-8) only. Go to next step.
2. Inspect knock sensor No. 1 connector for looseness and/or corrosion. Knock sensor No. 1 is located on passenger side of engine under intake manifold. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
3. Inspect knock sensor No. 1 for loose mounting to engine. Using Insert (3247), torque knock sensor No. 1 to 15 ft. lbs. (20 N.m) if necessary. If knock sensor No. 1 mounting was okay, go to next step. If knock sensor No. 1 mounting was repaired, erase DTC memory and test drive vehicle.
4. Disconnect knock sensor No. 1 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 1 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 1. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 1 and test box socket A13. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
8. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
9. Inspect knock sensor No. 2 connector for looseness and/or corrosion. Knock sensor No. 2 is located on driver side of engine under intake manifold. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
10. Inspect knock sensor No. 2 for loose mounting to engine. Using Insert (3247), torque knock sensor No. 2 to 15 ft. lbs. (20 N.m) if necessary. If knock sensor No. 2 mounting was okay, go to next step. If knock sensor No. 2 mounting was repaired, erase DTC memory and test drive vehicle.
11. Disconnect knock sensor No. 2 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 2 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 2. Erase DTC memory and test drive vehicle.
12. Using VAG 1598/19 test box connected to PCM wiring harness, check knock sensor No. 2 harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
13. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 1 and test box socket A15. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
14. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
15. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. Refer to «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0332/16716 - KNOCK SENSOR NO. 2 CKT LOW INPUT (BANK 2)

Note. DTC is set if knock sensor output voltage is less than .2 volts, coolant temperature more than 68°F (20°C), engine speed more than 3500 RPM and engine load more than 16 percent. Ignition timing will be retarded 12° according to ignition map in PCM.

1. If DTC P0327/16711 KNOCK SENSOR NO. 1 CIRCUIT LOW INPUT (BANK 1 OR SINGLE SENSOR) is also set in memory, perform procedures in test steps 2)-8), then continue and perform test steps 9)-15). If DTC P0327/16711 KNOCK SENSOR NO. 1 CIRCUIT LOW INPUT (BANK 1 OR SINGLE SENSOR) is not also set in memory, perform test steps 2)-8) only. Go to next step.
2. Inspect knock sensor No. 2 connector for looseness and/or corrosion. Knock sensor No. 2 is located on driver side of engine under intake manifold. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
3. Inspect knock sensor No. 2 for loose mounting to engine. Using Insert (3247), torque knock sensor No. 2 to 15 ft. lbs. (20 N.m) if necessary. If knock sensor No. 2 mounting was okay, go to next step. If knock sensor No. 2 mounting was repaired, erase DTC memory and test drive vehicle.
4. Disconnect knock sensor No. 2 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 2 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 2. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 1 and test box socket A15. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
8. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
9. Inspect knock sensor No. 1 connector for looseness and/or corrosion. Knock sensor No. 1 is located on passenger side of engine under intake manifold. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
10. Inspect knock sensor No. 1 for loose mounting to engine. Using Insert (3247), torque knock sensor No. 1 to 15 ft. lbs. (20 N.m) if necessary. If knock sensor No. 1 mounting was okay, go to next step. If knock sensor No. 1 mounting was repaired, erase DTC memory and test drive vehicle.
11. Disconnect knock sensor No. 1 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 1 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 1. Erase DTC memory and test drive vehicle.
12. Using VAG 1598/19 test box connected to PCM wiring harness, check knock sensor No. 1 harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
13. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 1 and test box socket A13. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
14. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and in this article.
15. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0337/16721 - CRANKSHAFT POSITION SENSOR CKT LOW INPUT

Note. DTC is set when crankshaft position sensor signal is not seen for more than 3 seconds with engine speed 25-400 RPM.

1. Inspect Crankshaft Position (CKP) sensor connector for looseness and/or corrosion. CKP sensor is located on driver side of cylinder block. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Ensure CKP sensor is correctly installed. Check distance between CKP sensor and groove on crankshaft. Maximum distance is .053" (1.3 mm). Repair as necessary. If sensor installation was not repaired, go to next step. If sensor installation was repaired, erase DTC memory and test drive vehicle.
3. Disconnect CKP sensor connector. Using a DVOM, measure resistance between CKP sensor connector (sensor side) terminals No. 1 and 2. Resistance should be approximately 1000 ohms. If resistance is to specification, go to next step. If resistance is not to specification, replace CKP sensor. Erase DTC memory and test drive vehicle.
4. Connect DVOM between CKP sensor connector (sensor side) terminals No. 1 and 3, then terminals No. 2 and 3. Resistance should be infinite (open). If resistance readings are infinite, go to next step. If resistance readings are not infinite, replace CKP sensor. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between CKP sensor connector (harness side) terminal No. 2 and engine ground. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Using DVOM, check resistance between CKP sensor connector (harness side) terminal No. 1 and test box socket A9. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and in this article.
8. Using DVOM, check resistance between CKP sensor connector (harness side) terminal No. 2 and test box socket A10. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0401/16785 - EGR FLOW INSUFFICIENT DETECTED

Note. DTC is set when coolant temperature is more than 162°F (72°C), open idle switch, throttle angle less than 42.5 degrees, vehicle speed 44-66 MPH, EGR duty cycle more than 50 percent, engine speed 1500-3300 RPM, and engine load 23-60 percent, with EGR temperature signal less than 122°F (50°C) for more than 34 seconds.

1. Inspect EGR vacuum hose for kinks, disconnection from EGR valve and leaks. Repair vacuum hose as necessary. If vacuum hose was not repaired, go to next step. If vacuum hose was repaired, erase DTC memory and test drive vehicle.
2. Inspect vacuum hose between EGR vacuum regulator solenoid valve and EGR valve for disconnection and leaks. Repair vacuum hose as necessary. If vacuum hose was not repaired, go to next step. If vacuum hose was repaired, erase DTC memory and test drive vehicle.
3. Disconnect EGR vacuum regulator solenoid valve electrical connector. Using a DVOM, measure resistance between EGR vacuum regulator solenoid valve terminals. Resistance should be 25-35 ohms. If resistance is to specification, go to next step. If resistance is not to specification, replace EGR vacuum regulator solenoid valve. Erase DTC memory and test drive vehicle.
4. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light. If voltage tester does not light, go to next step. If voltage tester lights, go to step 8).
5. Check fuse for EGR vacuum regulator solenoid valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
6. Using a DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Repair fuel pump relay circuit or replace fuel pump relay as necessary. Erase DTC memory and test drive vehicle. If fuel pump relay triggering is okay, go to next step.
7. Repair wiring as necessary. Erase DTC memory and test drive vehicle. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
8. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminals No. 1 and 2. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EGR vacuum regulator solenoid valve. Voltage tester should flash. If voltage tester flashes, circuit is okay. Go to step 13). If voltage tester lights up constantly or does not flash, go to next step.
9. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D", and "E".
10. If voltage tester had lit up constantly, go to step 13). If voltage tester did not flash, using DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 12).
11. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
12. Using DVOM, check for short to B+ between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, go to step 14).
13. Using DVOM, check for a short to ground between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If a short to ground is not present, circuit is okay. Go to step 14). If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.
14. Inspect EGR vacuum hose for kinks, disconnection from EGR valve and leaks. Repair vacuum hose as necessary. If vacuum hose was not repaired, go to next step. If vacuum hose was repaired, erase DTC memory and test drive vehicle.
15. Ensure engine oil temperature is a minimum of 122°F (50°C). Start engine and let it idle. Disconnect vacuum hose at EGR valve. Connect a hand-held vacuum pump to EGR valve. Apply vacuum to EGR valve. Idle quality should deteriorate. If idle quality deteriorates, EGR system is okay. Erase DTC memory and test drive vehicle.
16. If idle quality does not deteriorate, replace EGR valve if necessary. Erase DTC memory and test drive vehicle.
17. After performing entire test procedure, if all electrical circuits test good and EGR valve is mechanically functional, and DTC returns, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0402/16786 - EGR FLOW EXCESSIVE DETECTED

Note. DTC is set after a cold start when coolant temperature reaches 95°F (35°C) and EGR temperature is more than 122°F (50°C).

1. Inspect EGR vacuum hose for kinks, disconnection from EGR valve and leaks. Repair vacuum hose as necessary. If vacuum hose was not repaired, go to next step. If vacuum hose was repaired, erase DTC memory and test drive vehicle.
2. Disconnect EGR vacuum regulator solenoid valve electrical connector. Using a DVOM, measure resistance between EGR vacuum regulator solenoid valve terminals. Resistance should be 25-35 ohms. If resistance is to specification, go to next step. If resistance is not to specification, replace EGR vacuum regulator solenoid valve. Erase DTC memory and test drive vehicle.
3. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light. If voltage tester does not light, go to next step. If voltage tester lights, go to step 8).
4. Check fuse for EGR vacuum regulator solenoid valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
5. Using a DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Repair fuel pump relay circuit or replace fuel pump relay as necessary. Erase DTC memory and test drive vehicle. If fuel pump relay triggering is okay, go to next step.
6. Repair wiring as necessary. Erase DTC memory and test drive vehicle. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
7. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminals No. 1 and 2. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EGR vacuum regulator solenoid valve. Voltage tester should flash. If voltage tester flashes, circuit is okay. Go to step 12). If voltage tester lights up constantly or does not flash, go to next step.
8. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
9. If voltage tester had lit up constantly, go to step 12). If voltage tester did not flash, using DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 11).
10. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
11. Using DVOM, check for short to B+ between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, go to step 13).
12. Using DVOM, check for a short to ground between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If a short to ground is not present, circuit is okay. Go to step 13). If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle..
13. Inspect EGR vacuum hose for kinks, disconnection from EGR valve and leaks. Repair vacuum hose as necessary. If vacuum hose was not repaired, go to next step. If vacuum hose was repaired, erase DTC memory and test drive vehicle.
14. Ensure engine oil temperature is a minimum of 122°F (50°C). Start engine and let it idle. Disconnect vacuum hose at EGR valve. Connect a hand-held vacuum pump to EGR valve. Apply vacuum to EGR valve. Idle quality should deteriorate. If idle quality deteriorates, EGR system is okay. Erase DTC memory and test drive vehicle.
15. If idle quality does not deteriorate, replace EGR valve if necessary. Erase DTC memory and test drive vehicle.
16. After performing entire test procedure, if all electrical circuits test good and EGR valve is mechanically functional, and DTC returns, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0422/16806 - MAIN CATALYST EFFICIENCY BELOW THRESHOLD (BANK 1)

Note. PCM uses HO2S in front of, and behind 3-way catalyst to determine deterioration of 3-way catalyst using oxygen storage capability of catalyst.

1. Bank 1 3-way catalyst is located on passenger side of vehicle. If no other DTCs are set in memory, go to next step. If any other DTCs are set in memory, perform testing for other DTCs first. If after repairing other DTCs and clearing codes, this DTC returns, go to next step.
2. Possible cause for DTC may be catalyst is chemically or thermally aged or mechanically damaged. Replace 3-way catalyst. Erase DTC memory and test drive vehicle.

DTC P0432/16806 - MAIN CATALYST EFFICIENCY BELOW THRESHOLD (BANK 2)

Note. PCM uses HO2S in front of, and behind 3-way catalyst to determine deterioration of 3-way catalyst using oxygen storage capability of catalyst.

1. Bank 2 3-way catalyst is located on driver side of vehicle. If no other DTCs are set in memory, go to next step. If any other DTCs are set in memory, perform testing for other DTCs first. If after repairing other DTCs and clearing codes, this DTC returns, go to next step.
2. Possible cause for DTC may be catalyst is chemically or thermally aged or mechanically damaged. Replace 3-way catalyst. Erase DTC memory and test drive vehicle.

DTC P0440/16824 - EVAP SYSTEM MALFUNCTION

Note. PCM uses EVAP differential pressure sensor to measure pressure between EVAP canister and EVAP canister purge solenoid valve with purge solenoid valve open and closed. If difference between 2 pressures is less than .06-.33 psi (4-23 mbar) (depending on air pressure), DTC is set.

1. Inspect EVAP system for kinks and/or pinched hoses. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
2. Inspect EVAP system hoses between intake manifold and EVAP canister purge regulator valve, EVAP canister purge regulator valve and EVAP canister, and EVAP canister sensor and EVAP canister. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
3. Disconnect EVAP canister purge valve electrical connector. Using DVOM, check EVAP canister purge valve resistance. Measure resistance across EVAP canister purge valve terminals. Resistance should be 20-28 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace EVAP canister purge valve. Erase DTC memory and test drive vehicle.
4. With ignition on, connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminal No. 1 and ground. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for EVAP canister purge valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
5. Using a DVOM, check wiring between EVAP canister purge valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
6. Connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EVAP canister purge valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, ensure EVAP canister purge valve is not mechanically binding. Replace as necessary. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
9. Inspect EVAP system hoses between EVAP canister and throttle body. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
10. Disconnect EVAP canister differential pressure sensor electrical connector. EVAP canister differential pressure sensor is located in right front corner of engine compartment. Turn ignition on. Using DVOM, check voltage on EVAP differential pressure sensor harness connector between terminals No. 1 (ground) and 3 (B+). Voltage should be approximately 5 volts. If voltage is within specification, go to step 14). If voltage is not within specification, go to next step.
11. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
12. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 1 and test box socket C2. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
13. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 3 and test box socket C6. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
14. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 2 and test box socket B16. If continuity is present, circuit is okay. Replace EVAP differential pressure sensor. Erase DTC memory and test drive vehicle.
15. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle.

DTC P0452/16836 - EVAP SYSTEM PRESSURE SENSOR LOW INPUT

Note. DTC is set soon after engine start if EVAP differential pressure sensor signal is less than .1 volt for more than 2 seconds with EVAP emissions valve duty cycle more than 91 percent (100 percent equals valve closed).

1. Inspect EVAP canister differential pressure sensor connector for looseness and/or corrosion. EVAP canister differential pressure sensor is located in right front corner of engine compartment. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Inspect EVAP system hoses between EVAP canister and throttle body. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
3. Disconnect EVAP canister differential pressure sensor electrical connector. EVAP canister differential pressure sensor is located in right front corner of engine compartment. Turn ignition on. Using DVOM, check voltage on EVAP differential pressure sensor harness connector between terminals No. 1 (ground) and 3 (B+). Voltage should be approximately 5 volts. If voltage is within specification, go to step 7). If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 1 and test box socket C2. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
6. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 3 and test box socket C6. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
7. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 2 and test box socket B16. If continuity is present, circuit is okay. Replace EVAP differential pressure sensor. Erase DTC memory and test drive vehicle.
8. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0453/16837 - EVAP SYSTEM PRESSURE SENSOR HIGH INPUT

Note. DTC is set soon after engine start if EVAP differential pressure sensor signal is less than .1 volt for more than 2 seconds with EVAP emissions valve duty cycle more than 91 percent (100 percent equals valve closed).

1. Inspect EVAP canister differential pressure sensor connector for looseness and/or corrosion. EVAP canister differential pressure sensor is located in right front corner of engine compartment. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Inspect EVAP system hoses between EVAP canister and throttle body. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
3. Disconnect EVAP canister differential pressure sensor electrical connector. EVAP canister differential pressure sensor is located in right front corner of engine compartment. Turn ignition on. Using DVOM, check voltage on EVAP differential pressure sensor harness connector between terminals No. 1 (ground) and 3 (B+). Voltage should be approximately 5 volts. If voltage is within specification, go to step 7). If voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 1 and test box socket C2. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
6. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 3 and test box socket C6. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
7. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 2 and test box socket B16. If continuity is present, circuit is okay. Replace EVAP differential pressure sensor. Erase DTC memory and test drive vehicle.
8. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P0461/16845 - FUEL LEVEL SENSOR CIRCUIT RANGE/PERFORMANCE

Note. DTC is set with ignition on when voltage signal is more than 10.8 volts for more than 15 seconds. If fuel level in fuel tank is too low (less than 3.2 gallons), combustion misfire, HO2S and fuel system malfunctions can occur. If any of these malfunctions occur, DTC P0461/16845 is also set.

1. Ensure PCM coding is correct. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. Ensure fuel tank contains more than 3.2 gallons of fuel. Ensure fuel gauge in instrument cluster if functioning properly. Correct problems as necessary. Erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
3. Using DVOM, check wiring harness between PCM and instrument cluster. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Repair wiring harness as necessary. Erase DTC memory and test drive vehicle.

DTC P0501/16885 - VEHICLE SPEED SENSOR RANGE/PERFORMANCE

Note. DTC is set after engine start when coolant temperature is more than 176°F (80°C) with engine speed between 1300-6000 RPM when Vehicle Speed Sensor (VSS) signal is less than one MPH during a deceleration fuel shut-off. Deceleration fuel shut-off must be longer then 3 seconds.

1. Turn ignition off. Disconnect Powertrain Control Mod.
2. If voltage tester does not perform as specified, go to next step. If voltage tester performs as specified, circuit is okay. Erase DTC memory and test drive vehicle.
3. Using DVOM, check wiring harness between test box socket 13X and VSS, and test box socket C13 and VSS. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Repair wiring harness as necessary. If wiring is okay, replace VSS. Perform steps 2) and 3) again. After replacing VSS, if voltage tester does not perform as specified, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P0605/16989 - PCM ROM ERROR

Note. DTC is set in ROM/RAM or EEPROM when PCM recognizes internal failures.

Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P0706/17090 - TRANS RANGE SENSOR CKT RANGE/PERFORMANCE

Note. VAG 1551 scan tool is necessary to perform procedure.

1. Ensure PCM coding is correct. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If PCM coding is correct, go to next step. If PCM coding was incorrect, erase DTC memory and test drive vehicle. NOTE: During next step, only look at fields identified in VAG 1551 display, ignore fields with an X.
2. Using VAG 1551 scan tool, use READ MEASURING VALUE BLOCK mode, function 08, display group 04. With transmission selector lever in "P" or "N". VAG 1551 should display XXX_1X. Apply brake and put transmission selector lever in "1", "2", "3", "R" and "D". VAG 1551 should display XXX_0X. If VAG 1551 scan tool display did not change even though PCM coding is correct, go to next step. If VAG 1551 scan tool display was correct, erase DTC memory and test drive vehicle.
3. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
4. With ignition on, connect VAG 1527B voltage tester between test box sockets 11B (signal) and 10B (constant B+). Voltage tester should light up with transmission selector lever in "P" or "N", then go out in "1", "2", "3", "R" and "D". If voltage tester performs as specified, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
5. If voltage tester lights up constantly or not at all, check wiring harness for a short to ground, short to B+, or open circuit between PCM connector B terminal No. 11 and multifunction switch (selector lever switch). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. If wiring harness is okay, check multifunction switch (selector lever switch).

DTC P0707/17091 - TRANSMISSION RANGE SENSOR CKT LOW INPUT

Note. VAG 1551 scan tool is necessary to perform procedure.

1. Ensure PCM coding is correct. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If PCM coding is correct, go to next step. If PCM coding was incorrect, erase DTC memory and test drive vehicle. NOTE: During next step, only look at fields identified in VAG 1551 display, ignore fields with an X.
2. Using VAG 1551 scan tool, use READ MEASURING VALUE BLOCK mode, function 08, display group 04. With transmission selector lever in "P" or "N". VAG 1551 should display XXX_1X. Apply brake and put transmission selector lever in "1", "2", "3", "R" and "D". VAG 1551 should display XXX_0X. If VAG 1551 scan tool display did not change even though PCM coding is correct, go to next step. If VAG 1551 scan tool display was correct, erase DTC memory and test drive vehicle.
3. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
4. With ignition on, connect VAG 1527B voltage tester between test box sockets 11B (signal) and 10B (constant B+). Voltage tester should light up with transmission selector lever in "P" or "N", then go out in "1", "2", "3", "R" and "D". If voltage tester performs as specified, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
5. If voltage tester lights up constantly or not at all, check wiring harness for a short to ground, short to B+, or open circuit between PCM connector B terminal No. 11 and multifunction switch (selector lever switch). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. If wiring harness is okay, check multifunction switch (selector lever switch).

DTC P1101/17509 - HO2S VOLTAGE TOO LOW/AIR LEAK (BANK 1, SENSOR 1)

Note. DTC is set 123 seconds after engine start with coolant temperature more than 86°F (30°C) as soon as HO2S control has reached rich limit for 2 seconds more than 20 times without interruption.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Inspect exhaust system in front of HO2S for a leak. Repair exhaust system as necessary. If exhaust system was not repaired, go to next step. If exhaust system was repaired, erase DTC memory and test drive vehicle.
3. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
4. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A20. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1102/17510 - HO2S HEATER CKT SHRT TO B+ (BANK 1, SENS 1)

Note. DTC is set after engine start if heating current is more than 10 amps for more than 80 milliseconds with battery voltage 9-16 volts.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Black 4-pin connector located in right rear corner of engine compartment. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 2 and PCM connector terminal E10. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If resistance is not within specification, replace HO2S. Erase DTC memory and test drive vehicle.

DTC P1104/17512 - HO2S VOLTAGE TOO LOW/AIR LEAK (BANK 1, SENSOR 2)

Note. DTC is set 123 seconds after engine start if signal voltage is less than .040 volts for more than 60 seconds with coolant temperature more than 176°F (80°C), HO2S control active, engine speed 1500-5000 RPM, engine load 19-80 percent with HO2S heater switched on for at least 45 seconds.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Inspect exhaust system for a leak between HO2S located in front of passenger side catalytic converter and HO2S located behind passenger side catalytic converter. Repair exhaust system as necessary. If exhaust system was not repaired, go to next step. If exhaust system was repaired, erase DTC memory and test drive vehicle.
3. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminals No. 3 (ground) and 4 (signal). If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
4. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 3 (ground) and 4 (signal). Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 3 and test box socket C17. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket C20. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
8. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1105/17513 - HO2S HTR CKT SHRT TO B+ (BANK 1, SENSOR 2)

Note. HO2S heater behind 3-way catalytic converter is not switched on at engine start. Heater is switched on when calculated exhaust gas temperature is less than 586°F (308°).

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on passenger side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Green 4-pin connector located in right rear corner of engine compartment. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between PCM connector "E" terminals No. 2 and 8. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article. If resistance is not within specification, replace HO2S. Erase DTC memory and test drive vehicle.

DTC P1106/17514 - HO2S VOLTAGE TOO LOW/AIR LEAK (BANK 2, SENSOR 1)

Note. DTC is set 123 seconds after engine start with coolant temperature more than 86°F (30°C) as soon as HO2S control has reached rich limit for 2 seconds more than 20 times without interruption.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Inspect exhaust system in front of HO2S for a leak. Repair exhaust system as necessary. If exhaust system was not repaired, go to next step. If exhaust system was repaired, erase DTC memory and test drive vehicle.
3. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
4. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A21. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1107/17515 - HO2S HEATER CIRCUIT SHORT TO B+ (BANK 2, SENSOR 1)

Note. DTC is set after engine start if heating current is more than 10 amps for more than 80 milliseconds with battery voltage 9-16 volts.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Black 4-pin connector located near HO2S. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 2 and PCM connector terminal E9. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If resistance is not within specification, replace HO2S. Erase DTC memory and test drive vehicle.

DTC P1109/17517 - HO2S VOLTAGE TOO LOW/AIR LEAK (BANK 2, SENSOR 2)

Note. DTC is set 123 seconds after engine start if signal voltage is less than .040 volts for more than 60 seconds with coolant temperature more than 176°F (80°C), HO2S control active, engine speed 1500-5000 RPM, engine load 19-80 percent with HO2S heater switched on for at least 45 seconds.

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Inspect exhaust system for a leak between HO2S located in front of driver side catalytic converter and HO2S located behind driver side catalytic converter. Repair exhaust system as necessary. If exhaust system was not repaired, go to next step. If exhaust system was repaired, erase DTC memory and test drive vehicle.
3. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
4. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 3 and test box socket C17. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket C21. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
8. If an open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1110/17518 - HO2S HEATER CIRCUIT SHORT TO B+ (BANK 2, SENSOR 2)

Note. HO2S heater behind 3-way catalytic converter is not switched on at engine start. Heater is switched on when calculated exhaust gas temperature is less than 586°F (308°).

1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle behind 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect HO2S Brown 4-pin connector located in right rear corner of engine compartment. Start engine and let it idle. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 1 (B+) and 2 (ground). Voltage should be 12-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle.
3. Verify HO2S heater fuse is okay. Replace if necessary. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Using DVOM, check resistance between fuel pump relay fuse and HO2S connector (harness side). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
4. Using DVOM, check resistance between PCM connector "E" terminals No. 2 and 3. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
5. Using DVOM, check resistance between HO2S connector (sensor side) terminals No. 1 and 2. Resistance is approximately 2-5 ohms at room temperature. With small increases in temperature, resistance will increase sharply. If resistance is within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If resistance is not within specification, replace HO2S. Erase DTC memory and test drive vehicle.

DTC P1201/17609 - CYLINDER NO. 1 FUEL INJECTOR CIRCUIT ELECTRICAL MALFUNCTION

Note. If DTC P1201/17609, P1202/17610 and/or P1203/17611 is seen by PCM, HO2S control for cylinders on passenger side of engine is blocked. If all 6 fuel injector DTCs are set, DTC P1500/17908 will also be set.

1. If all 6 fuel injector DTCs are set, check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. If fuel pump relay is okay, go to next step. If fuel pump relay was replaced or repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
3. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 6).
5. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19/ test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between fuel injector harness connector No. 2 and test box socket D2. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 1. Erase DTC memory and test drive vehicle.
9. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1202/17610 - CYLINDER NO. 2 FUEL INJECTOR CIRCUIT ELECTRICAL MALFUNCTION

Note. If DTC P1201/17609, P1202/17610 and/or P1203/17611 is seen by PCM, HO2S control for cylinders on passenger side of engine is blocked. If all 6 fuel injector DTCs are set, DTC P1500/17908 will also be set.

1. If all 6 fuel injector DTCs are set, check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. If fuel pump relay is okay, go to next step. If fuel pump relay was replaced or repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
2. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
3. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 6).
5. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D2. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 2. Erase DTC memory and test drive vehicle.
9. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1203/17611 - CYLINDER NO. 3 FUEL INJECTOR CIRCUIT ELECTRICAL MALFUNCTION

Note. If DTC P1201/17609, P1202/17610 and/or P1203/17611 is seen by PCM, HO2S control for cylinders on passenger side of engine is blocked. If all 6 fuel injector DTCs are set, DTC P1500/17908 will also be set.

1. If all 6 fuel injector DTCs are set, check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. If fuel pump relay is okay, go to next step. If fuel pump relay was replaced or repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
2. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
3. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle.
4. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 6).
5. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D4. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 4. Erase DTC memory and test drive vehicle.
9. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1204/17612 - CYLINDER NO. 4 FUEL INJECTOR CIRCUIT ELECTRICAL MALFUNCTION

Note. If DTC P1204/17612, P1205/17613 and/or P1206/17614 is seen by PCM, HO2S control for cylinders on driver side of engine is blocked. If all 6 fuel injector DTCs are set, DTC P1500/17908 will also be set.

1. If all 6 fuel injector DTCs are set, check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. If fuel pump relay is okay, go to next step. If fuel pump relay was replaced or repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
2. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
3. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 6).
5. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D5. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 5. Erase DTC memory and test drive vehicle.
9. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1205/17613 - CYLINDER NO. 5 FUEL INJECTOR CIRCUIT ELECTRICAL MALFUNCTION

Note. If DTC P1204/17612, P1205/17613 and/or P1206/17614 is seen by PCM, HO2S control for cylinders on driver side of engine is blocked. If all 6 fuel injector DTCs are set, DTC P1500/17908 will also be set.

1. If all 6 fuel injector DTCs are set, check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. If fuel pump relay is okay, go to next step. If fuel pump relay was replaced or repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
2. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
3. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 6).
5. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D6. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 6. Erase DTC memory and test drive vehicle.
9. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1206/17614 - CYLINDER NO. 6 FUEL INJECTOR CIRCUIT ELECTRICAL MALFUNCTION

Note. If DTC P1204/17612, P1205/17613 and/or P1206/17614 is seen by PCM, HO2S control for cylinders on driver side of engine is blocked. If all 6 fuel injector DTCs are set, DTC P1500/17908 will also be set.

1. If all 6 fuel injector DTCs are set, check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. If fuel pump relay is okay, go to next step. If fuel pump relay was replaced or repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
2. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
3. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
4. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 6).
5. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
6. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D8. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 8. Erase DTC memory and test drive vehicle.
9. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1213/17621 - CYLINDER NO. 1 FUEL INJECTOR CKT SHORT TO B+

Note. If DTC P1213/17621, P1214/17622 and/or P1215/17623 is seen by PCM, corresponding fuel injector is not triggered and HO2S control for cylinders on passenger side of engine is blocked.

1. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
2. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 5).
4. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
5. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D1. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 1. Erase DTC memory and test drive vehicle.
8. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1214/17622 - CYLINDER NO. 2 FUEL INJECTOR CKT SHORT TO B+

Note. If DTC P1213/17621, P1214/17622 and/or P1215/17623 is seen by PCM, corresponding fuel injector is not triggered and HO2S control for cylinders on passenger side of engine is blocked.

1. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
2. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 5).
4. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
5. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D2. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 2. Erase DTC memory and test drive vehicle.
8. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1215/17623 - CYLINDER NO. 3 FUEL INJECTOR CKT SHRT TO B+

Note. If DTC P1213/17621, P1214/17622 and/or P1215/17623 is seen by PCM, corresponding fuel injector is not triggered and HO2S control for cylinders on passenger side of engine is blocked.

1. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
2. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 5).
4. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
5. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D4. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 4. Erase DTC memory and test drive vehicle.
8. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1216/17624 - CYLINDER NO. 4 FUEL INJECTOR CKT SHRT TO B+

Note. If DTC P1216/17624, P1217/17625 and/or P1218/17626 is seen by PCM, corresponding fuel injector is not triggered and HO2S control for cylinders on driver side of engine is blocked.

1. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
2. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 5).
4. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
5. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D5. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 5. Erase DTC memory and test drive vehicle.
8. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1217/17625 - CYLINDER NO. 5 FUEL INJECTOR CKT SHRT TO B+

Note. If DTC P1216/17624, P1217/17625 and/or P1218/17626 is seen by PCM, corresponding fuel injector is not triggered and HO2S control for cylinders on driver side of engine is blocked.

1. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
2. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 5).
4. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
5. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D6. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 6. Erase DTC memory and test drive vehicle.
8. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1218/17626 - CYLINDER NO. 6 FUEL INJECTOR CKT SHRT TO B+

Note. If DTC P1216/17624, P1217/17625 and/or P1218/17626 is seen by PCM, corresponding fuel injector is not triggered and HO2S control for cylinders on driver side of engine is blocked.

1. Turn ignition off. Disconnect fuel injector electrical connector. Using a DVOM, measure resistance across fuel injector terminals. See INJECTOR RESISTANCE table. If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. Erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step. INJECTOR RESISTANCE Application Ohms Bosch 15-17 Siemens 13.5-15.5
2. Check fuel pump relay. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Check fuel pump. See «BASIC TESTING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-basic-testing) article. Check fuse for fuel injectors. Repair components as necessary. If components are okay, go to next step. If any components were repaired, erase DTC memory and test drive vehicle. If no other DTCs are stored, go to next step.
3. With fuel injector connector disconnected, connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03, to trigger fuel pump relay. Voltage tester should light. If voltage tester lights, go to step 5).
4. If voltage tester does not light, check wiring harness between fuel injector harness connector terminal No. 1 and fuel injector fuse. Repair as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
5. Connect VAG 1527B voltage tester between fuel injector harness connector terminal No. 2 and battery voltage. Operate starter several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashed, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between fuel injector harness connector terminal No. 2 and test box socket D8. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit between fuel injector harness connector and PCM connector "D" terminal No. 8. Erase DTC memory and test drive vehicle.
8. Check voltage supply for PCM. See PCM VOLTAGE & GROUND CHECK in this article. Repair as necessary. Erase DTC memory and test drive vehicle. If voltage supply is okay, replace faulty PCM. Erase DTC memory and test drive vehicle.

DTC P1250/17658 - FUEL LEVEL TOO LOW

If this DTC is set in memory, this indicates there is less than 3.2 gallons of fuel in tank. Check fuel tank level and fill if necessary. Erase DTC memory and test drive vehicle.

DTC P1325/17733 - CYLINDER NO. 1 KNOCK CONTROL LIMIT ATTAINED

Note. DTC is set when ignition timing is fully retarded for more than 3 minutes.

1. If all 6 cylinders have reached knock control limit, poor fuel quality or loose engine accessories could be the cause. If fuel quality and engine accessories are okay, go to next step. If fuel quality is in question and/or engine accessories are suspect, fill fuel tank with premium fuel and/or tighten loose engine accessories. Erase DTC memory and test drive vehicle.
2. If knock control limit was reached for only cylinder No. 1, go to step 10). If knock control limit was reached for all cylinders on passenger side of engine, check knock sensor No. 1 for proper mounting. Knock sensor No. 1 (for cylinders No. 1-3) is located on passenger side of engine under intake manifold. Go to next step.
3. Inspect knock sensor No. 1 for loose mounting to engine. Using Insert (3247), torque knock sensor to 15 ft. lbs. (20 N.m) if necessary. If knock sensor mounting was okay, go to next step. If knock sensor mounting was repaired, erase DTC memory and test drive vehicle.
4. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
5. Disconnect knock sensor No. 1 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 1 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 1. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 1 and test box socket A13. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
9. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
10. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
11. Check engine for mechanical damage. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1326/17734 - CYLINDER NO. 2 KNOCK CONTROL LIMIT ATTAINED

Note. DTC is set when ignition timing is fully retarded for more than 3 minutes.

1. If all 6 cylinders have reached knock control limit, poor fuel quality or loose engine accessories could be the cause. If fuel quality and engine accessories are okay, go to next step. If fuel quality is in question and/or engine accessories are suspect, fill fuel tank with premium fuel and/or tighten loose engine accessories. Erase DTC memory and test drive vehicle.
2. If knock control limit was reached for only cylinder No. 2, go to step 10). If knock control limit was reached for all cylinders on passenger side of engine, check knock sensor No. 1 for proper mounting. Knock sensor No. 1 (for cylinders No. 1-3) is located on passenger side of engine under intake manifold. Go to next step.
3. Inspect knock sensor No. 1 for loose mounting to engine. Using Insert (3247), torque knock sensor to 15 ft. lbs. (20 N.m) if necessary. If knock sensor mounting was okay, go to next step. If knock sensor mounting was repaired, erase DTC memory and test drive vehicle.
4. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
5. Disconnect knock sensor No. 1 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 1 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 1. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 1 and test box socket A13. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
9. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
10. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
11. Check engine for mechanical damage. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1327/17735 - CYLINDER NO. 3 KNOCK CONTROL LIMIT ATTAINED

Note. DTC is set when ignition timing is fully retarded for more than 3 minutes.

1. If all 6 cylinders have reached knock control limit, poor fuel quality or loose engine accessories could be the cause. If fuel quality and engine accessories are okay, go to next step. If fuel quality is in question and/or engine accessories are suspect, fill fuel tank with premium fuel and/or tighten loose engine accessories. Erase DTC memory and test drive vehicle.
2. If knock control limit was reached for all cylinders on passenger side of engine, check knock sensor No. 1 for proper mounting. Knock sensor No. 1 (for cylinders No. 1-3) is located on passenger side of engine under intake manifold. Go to next step. If knock control limit was reached for only cylinder No. 3, go to step 10).
3. Inspect knock sensor No. 1 for loose mounting to engine. Using Insert (3247), torque knock sensor to 15 ft. lbs. (20 N.m) if necessary. If knock sensor mounting was okay, go to next step. If knock sensor mounting was repaired, erase DTC memory and test drive vehicle.
4. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
5. Disconnect knock sensor No. 1 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 1 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 1. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 1 and test box socket A13. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
9. Using DVOM, check resistance between knock sensor No. 1 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
10. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
11. Check engine for mechanical damage. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1328/17736 - CYLINDER NO. 4 KNOCK CONTROL LIMIT ATTAINED

Note. DTC is set when ignition timing is fully retarded for more than 3 minutes.

1. If all 6 cylinders have reached knock control limit, poor fuel quality or loose engine accessories could be the cause. If fuel quality and engine accessories are okay, go to next step. If fuel quality is in question and/or engine accessories are suspect, fill fuel tank with premium fuel and/or tighten loose engine accessories. Erase DTC memory and test drive vehicle.
2. If knock control limit was reached for all cylinders on driver side of engine, check knock sensor No. 2 for proper mounting. Knock sensor No. 2 (for cylinders No. 2-6) is located on driver side of engine under intake manifold. Go to next step. If knock control limit was reached for only cylinder No. 4, go to step 10).
3. Inspect knock sensor No. 2 for loose mounting to engine. Using Insert (3247), torque knock sensor to 15 ft. lbs. (20 N.m) if necessary. If knock sensor mounting was okay, go to next step. If knock sensor mounting was repaired, erase DTC memory and test drive vehicle.
4. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
5. Disconnect knock sensor No. 2 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 2 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 2. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 1 and test box socket A15. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
9. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
10. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
11. Check engine for mechanical damage. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1329/17737 - CYLINDER NO. 5 KNOCK CONTROL LIMIT ATTAINED

Note. DTC is set when ignition timing is fully retarded for more than 3 minutes.

1. If all 6 cylinders have reached knock control limit, poor fuel quality or loose engine accessories could be the cause. If fuel quality and engine accessories are okay, go to next step. If fuel quality is in question and/or engine accessories are suspect, fill fuel tank with premium fuel and/or tighten loose engine accessories. Erase DTC memory and test drive vehicle.
2. If knock control limit was reached for all cylinders on driver side of engine, check knock sensor No. 2 for proper mounting. Knock sensor No. 2 (for cylinders No. 2-6) is located on driver side of engine under intake manifold. Go to next step. If knock control limit was reached for only cylinder No. 5, go to step 10).
3. Inspect knock sensor No. 2 for loose mounting to engine. Using Insert (3247), torque knock sensor to 15 ft. lbs. (20 N.m) if necessary. If knock sensor mounting was okay, go to next step. If knock sensor mounting was repaired, erase DTC memory and test drive vehicle.
4. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
5. Disconnect knock sensor No. 2 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 2 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 2. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 1 and test box socket A15. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
9. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
10. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
11. Check engine for mechanical damage. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1330/17738 - CYLINDER NO. 5 KNOCK CONTROL LIMIT ATTAINED

Note. DTC is set when ignition timing is fully retarded for more than 3 minutes.

1. If all 6 cylinders have reached knock control limit, poor fuel quality or loose engine accessories could be the cause. If fuel quality and engine accessories are okay, go to next step. If fuel quality is in question and/or engine accessories are suspect, fill fuel tank with premium fuel and/or tighten loose engine accessories. Erase DTC memory and test drive vehicle.
2. If knock control limit was reached for only cylinder No. 6, go to step 10). If knock control limit was reached for all cylinders on driver side of engine, check knock sensor No. 2 for proper mounting. Knock sensor No. 2 (for cylinders No. 2-6) is located on driver side of engine under intake manifold. Go to next step.
3. Inspect knock sensor No. 2 for loose mounting to engine. Using Insert (3247), torque knock sensor to 15 ft. lbs. (20 N.m) if necessary. If knock sensor mounting was okay, go to next step. If knock sensor mounting was repaired, erase DTC memory and test drive vehicle.
4. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
5. Disconnect knock sensor No. 2 3-pin connector. Using a DVOM, check all 3 terminals in knock sensor No. 2 connector (sensor side) for shorting to each other. If a short circuit is not present, go to next step. If a short circuit is present, replace knock sensor No. 2. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 1 and test box socket A15. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 2 and test box socket A14. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
9. Using DVOM, check resistance between knock sensor No. 2 connector (harness side) terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
10. Check engine accessories for looseness. Repair as necessary. If engine accessories are okay, go to next step. If engine accessories were repaired, erase DTC memory and test drive vehicle.
11. Check engine for mechanical damage. Repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1339/17747 - CRANKSHAFT POSITION SENSOR/ENGINE SPEED SENSOR CROSS CONNECTED

Note. DTC is set if crankshaft position sensor and engine speed sensor are cross connected.

Disconnect connectors and connect to correct sensor. Erase DTC memory and test drive vehicle.

DTC P1340/17748 - CAMSHAFT/CRANKSHAFT POSITION SENSOR SIGNALS OUT OF SEQUENCE

Note. DTC is set when crankshaft position sensor signal is always high with engine speed 50-4000 RPM, with more than 20 crankshaft sensor signals recognized.

1. Inspect Camshaft Position (CMP) sensor connector for looseness and/or corrosion. CMP sensor is located at rear of left cylinder head. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect Camshaft Position (CMP) sensor 3-pin connector. Turn ignition on. Connect a DVOM between CMP sensor connector terminals No. 1 and 3.
3. Voltage should be 9 volts. If voltage is within specification, go to next step. If voltage is not to specification, repair open or short in wiring harness between CMP sensor connector and Powertrain Control Module (PCM). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between CMP sensor harness connector terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
6. Using DVOM, check resistance between CMP sensor harness connector terminal No. 1 and test box socket A2. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle.If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Disconnect 4-pin ignition coil power output stage connector. Ignition coil power output stage is located in right front corner of engine compartment. With CMP sensor connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between CMP sensor connector terminals No. 1 and 2. Operate starter for several seconds. Voltage tester should briefly flash every other engine rotation. If voltage tester does not flash as specified, go to next step. If voltage tester flashes as specified, go to step 10).
8. Turn ignition off. Disconnect CMP sensor 3-pin connector. Using DVOM, check resistance between CMP sensor harness connector terminal No. 2 and test box socket B2. Maximum resistance is one ohm. If resistance is within specification, go to step 10). If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, go to next step.
9. Turn ignition on. Using DVOM, check voltage between test box socket B2 and ground. Voltage should be 4 volts minimum. If voltage is within specification, replace CMP sensor. Erase DTC memory and test drive vehicle. If voltage is not within specification, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
10. Inspect CMP sensor for oil/dirt contamination caused by leaking seal on cylinder head. If CMP sensor is not contaminated, go to next step. If CMP sensor is contaminated, replace seal on cylinder head. Erase DTC memory and test drive vehicle.
11. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1341/17749 - IGNITION COIL POWER OUTPUT STAGE 1 SHORT TO GROUND

1. Inspect power output stage connectors for looseness and/or corrosion. Power output stage is located in right front corner of engine compartment. Repair connectors as necessary. If connectors were not repaired, go to next step. If connectors were repaired, erase DTC memory and test drive vehicle.
2. Disconnect ignition coil power output stage 3-pin connector. Turn ignition on. Using a DVOM, measure voltage between each harness connector terminal and ground. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
3. Disconnect power output stage 4-pin connector. Turn ignition on. Using a DVOM, measure voltage between power output stage 4-pin harness connector terminal No. 2 and battery voltage. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
4. Disconnect all 6 fuel injector connectors. Connect VAG 1527B voltage tester between power output stage 4-pin harness connector terminals No. 1, 3 and 4 in sequence and ground. Operate starter for several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashes, wiring is okay. If DTCs P1394/17802 and P1395/17803 are also set, replace power output stage. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 1 and test box socket B7. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 3 and test box socket B6. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article.
8. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 4 and test box socket B5. Continuity should be present. If continuity is present, circuit is okay. Erase DTC memory and test drive vehicle. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1343/17751 - IGNITION COIL POWER OUTPUT STAGE 2 SHORT TO GROUND

1. Inspect power output stage connectors for looseness and/or corrosion. Power output stage is located in right front corner of engine compartment. Repair connectors as necessary. If connectors were not repaired, go to next step. If connectors were repaired, erase DTC memory and test drive vehicle.
2. Disconnect ignition coil power output stage 3-pin connector. Turn ignition on. Using a DVOM, measure voltage between each harness connector terminal and ground. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
3. Disconnect power output stage 4-pin connector. Turn ignition on. Using a DVOM, measure voltage between power output stage 4-pin harness connector terminal No. 2 and battery voltage. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
4. Disconnect all 6 fuel injector connectors. Connect VAG 1527B voltage tester between power output stage 4-pin harness connector terminals No. 1, 3 and 4 in sequence and ground. Operate starter for several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashes, wiring is okay. If DTCs P1394/17802 and P1395/17803 are also set, replace power output stage. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 1 and test box socket B7. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
7. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 3 and test box socket B6. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 4 and test box socket B5. Continuity should be present. If continuity is present, circuit is okay. Erase DTC memory and test drive vehicle. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1345/17753 - IGNITION COIL POWER OUTPUT STAGE 2 SHORT TO GROUND

1. Inspect power output stage connectors for looseness and/or corrosion. Power output stage is located in right front corner of engine compartment. Repair connectors as necessary. If connectors were not repaired, go to next step. If connectors were repaired, erase DTC memory and test drive vehicle.
2. Disconnect ignition coil power output stage 3-pin connector. Turn ignition on. Using a DVOM, measure voltage between each harness connector terminal and ground. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
3. Disconnect power output stage 4-pin connector. Turn ignition on. Using a DVOM, measure voltage between power output stage 4-pin harness connector terminal No. 2 and battery voltage. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
4. Disconnect all 6 fuel injector connectors. Connect VAG 1527B voltage tester between power output stage 4-pin harness connector terminals No. 1, 3 and 4 in sequence and ground. Operate starter for several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashes, wiring is okay. If DTCs P1394/17802 and P1395/17803 are also set, replace power output stage. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 1 and test box socket B7. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 3 and test box socket B6. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
8. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 4 and test box socket B5. Continuity should be present. If continuity is present, circuit is okay. Erase DTC memory and test drive vehicle. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and TEST DRIVE in this article.

DTC P1391/17799 - CMP SENSOR SHORT TO GROUND

Note. DTC is set when crankshaft position sensor signal is always low with engine speed 50-4000 RPM, with more than 3 crankshaft sensor signals recognized.

1. Inspect Camshaft Position (CMP) sensor connector for looseness and/or corrosion. CMP sensor is located at rear of left cylinder head. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect Camshaft Position (CMP) sensor 3-pin connector. Turn ignition on. Connect a DVOM between CMP sensor connector terminals No. 1 and 3.
3. Voltage should be 9 volts. If voltage is within specification, go to next step. If voltage is not to specification, repair open or short in wiring harness between CMP sensor connector and Powertrain Control Module (PCM). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between CMP sensor harness connector terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
6. Using DVOM, check resistance between CMP sensor harness connector terminal No. 1 and test box socket A2. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
7. Disconnect 4-pin ignition coil power output stage connector. Ignition coil power output stage is located in right front corner of engine compartment. With CMP sensor connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between CMP sensor connector terminals No. 1 and 2. Operate starter for several seconds. Voltage tester should briefly flash every other engine rotation. If voltage tester does not flash as specified, go to next step. If voltage tester flashes as specified, go to step 10).
8. Turn ignition off. Disconnect CMP sensor 3-pin connector. Using DVOM, check resistance between CMP sensor harness connector terminal No. 2 and test box socket B2. Maximum resistance is one ohm. If resistance is within specification, go to step 10). If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, go to next step.
9. Turn ignition on. Using DVOM, check voltage between test box socket B2 and ground. Voltage should be 4 volts minimum. If voltage is within specification, replace CMP sensor. Erase DTC memory and test drive vehicle. If voltage is not within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) this article.
10. Inspect CMP sensor for oil/dirt contamination caused by leaking seal on cylinder head. If CMP sensor is not contaminated, go to next step. If CMP sensor is contaminated, replace seal on cylinder head. Erase DTC memory and test drive vehicle.
11. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1392/17800 - CMP SENSOR OPEN CIRCUIT OR SHORT TO B+

Note. DTC is set when crankshaft position sensor signal is always high with engine speed 50-4000 RPM, with more than 20 crankshaft sensor signals recognized.

1. Inspect Camshaft Position (CMP) sensor connector for looseness and/or corrosion. CMP sensor is located at rear of left cylinder head. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Turn ignition off. Disconnect Camshaft Position (CMP) sensor 3-pin connector. Turn ignition on. Connect a DVOM between CMP sensor connector terminals No. 1 and 3.
3. Voltage should be 9 volts. If voltage is within specification, go to next step. If voltage is not to specification, repair open or short in wiring harness between CMP sensor connector and Powertrain Control Module (PCM). See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
5. Using DVOM, check resistance between CMP sensor harness connector terminal No. 3 and engine ground. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
6. Using DVOM, check resistance between CMP sensor harness connector terminal No. 1 and test box socket A2. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
7. Disconnect 4-pin ignition coil power output stage connector. Ignition coil power output stage is located in right front corner of engine compartment. With CMP sensor connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between CMP sensor connector terminals No. 1 and 2. Operate starter for several seconds. Voltage tester should briefly flash every other engine rotation. If voltage tester does not flash as specified, go to next step. If voltage tester flashes as specified, go to step 10).
8. Turn ignition off. Disconnect CMP sensor 3-pin connector. Using DVOM, check resistance between CMP sensor harness connector terminal No. 2 and test box socket B2. Maximum resistance is one ohm. If resistance is within specification, go to step 10). If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, go to next step.
9. Turn ignition on. Using DVOM, check voltage between test box socket B2 and ground. Voltage should be 4 volts minimum. If voltage is within specification, replace CMP sensor. Erase DTC memory and test drive vehicle. If voltage is not within specification, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
10. Inspect CMP sensor for oil/dirt contamination caused by leaking seal on cylinder head. If CMP sensor is not contaminated, go to next step. If CMP sensor is contaminated, replace seal on cylinder head. Erase DTC memory and test drive vehicle.
11. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1393/17801 - IGNITION COIL POWER OUTPUT STAGE 1 ELECTRICAL MALFUNCTION

1. Inspect power output stage connectors for looseness and/or corrosion. Power output stage is located in right front corner of engine compartment. Repair connectors as necessary. If connectors were not repaired, go to next step. If connectors were repaired, erase DTC memory and test drive vehicle.
2. Disconnect ignition coil power output stage 3-pin connector. Turn ignition on. Using a DVOM, measure voltage between each harness connector terminal and ground. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
3. Disconnect power output stage 4-pin connector. Turn ignition on. Using a DVOM, measure voltage between power output stage 4-pin harness connector terminal No. 2 and battery voltage. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
4. Disconnect all 6 fuel injector connectors. Connect VAG 1527B voltage tester between power output stage 4-pin harness connector terminals No. 1, 3 and 4 in sequence and ground. Operate starter for several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashes, wiring is okay. If DTCs P1394/17802 and P1395/17803 are also set, replace power output stage. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 1 and test box socket B7. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
7. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 3 and test box socket B6. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
8. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 4 and test box socket B5. Continuity should be present. If continuity is present, circuit is okay. Erase DTC memory and test drive vehicle. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1394/17802 - IGNITION COIL POWER OUTPUT STAGE 2 ELECTRICAL MALFUNCTION

1. Inspect power output stage connectors for looseness and/or corrosion. Power output stage is located in right front corner of engine compartment. Repair connectors as necessary. If connectors were not repaired, go to next step. If connectors were repaired, erase DTC memory and test drive vehicle.
2. Disconnect ignition coil power output stage 3-pin connector. Turn ignition on. Using a DVOM, measure voltage between each harness connector terminal and ground. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
3. Disconnect power output stage 4-pin connector. Turn ignition on. Using a DVOM, measure voltage between power output stage 4-pin harness connector terminal No. 2 and battery voltage. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
4. Disconnect all 6 fuel injector connectors. Connect VAG 1527B voltage tester between power output stage 4-pin harness connector terminals No. 1, 3 and 4 in sequence and ground. Operate starter for several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashes, wiring is okay. If DTCs P1394/17802 and P1395/17803 are also set, replace power output stage. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 1 and test box socket B7. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 3 and test box socket B6. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
8. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 4 and test box socket B5. Continuity should be present. If continuity is present, circuit is okay. Erase DTC memory and test drive vehicle. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1395/17803 - IGNITION COIL POWER OUTPUT STAGE 3 ELECTRICAL MALFUNCTION

1. Inspect power output stage connectors for looseness and/or corrosion. Power output stage is located in right front corner of engine compartment. Repair connectors as necessary. If connectors were not repaired, go to next step. If connectors were repaired, erase DTC memory and test drive vehicle.
2. Disconnect ignition coil power output stage 3-pin connector. Turn ignition on. Using a DVOM, measure voltage between each harness connector terminal and ground. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
3. Disconnect power output stage 4-pin connector. Turn ignition on. Using a DVOM, measure voltage between power output stage 4-pin harness connector terminal No. 2 and battery voltage. Voltage should be approximately battery voltage. If voltage is within specification, go to next step. If voltage is not to specification, repair wiring harness as necessary. Erase DTC memory and test drive vehicle.
4. Disconnect all 6 fuel injector connectors. Connect VAG 1527B voltage tester between power output stage 4-pin harness connector terminals No. 1, 3 and 4 in sequence and ground. Operate starter for several seconds. Voltage tester should flash. If voltage tester does not flash, go to next step. If voltage tester flashes, wiring is okay. If DTCs P1394/17802 and P1395/17803 are also set, replace power output stage. Erase DTC memory and test drive vehicle.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 1 and test box socket B7. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
7. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 3 and test box socket B6. Continuity should be present. If continuity is present, go to next step. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
8. Using DVOM, check for continuity between power output stage 4-pin harness connector terminal No. 4 and test box socket B5. Continuity should be present. If continuity is present, circuit is okay. Erase DTC memory and test drive vehicle. If continuity is not present, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1396/17804 - ENGINE SPEED SENSOR MISSING TOOTH

Note. DTC is set when engine speed sensor does not supply 270 engine speed pulses per engine revolution.

Remove starter. Visually inspect starter ring gear. Replace starter ring gear if broken teeth are found. Erase DTC memory and test drive vehicle.

DTC P1400/17808 - EGR VALVE CIRCUIT ELECTRICAL MALFUNCTION

Note. DTC is set with engine speed less than 900 RPM, engine load less than 25 percent, EGR valve duty cycle less than 20 percent when PCM output of EGR valve is low for more than 1.2 seconds.

1. Inspect EGR vacuum regulator solenoid valve connector for looseness and/or corrosion. EGR vacuum regulator solenoid valve is located in center rear of engine compartment. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect EGR vacuum regulator solenoid valve electrical connector. Using a DVOM, measure resistance between EGR vacuum regulator solenoid valve terminals. Resistance should be 25-35 ohms. If resistance is to specification, go to next step. If resistance is not to specification, replace EGR vacuum regulator solenoid valve. Erase DTC memory and test drive vehicle.
3. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light. If voltage tester does not light, go to next step. If voltage tester lights, go to step 7).
4. Check fuse for EGR vacuum regulator solenoid valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
5. Using a DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Repair fuel pump relay circuit or replace fuel pump relay as necessary. Erase DTC memory and test drive vehicle. If fuel pump relay triggering is okay, go to next step.
6. Repair wiring as necessary. Erase DTC memory and test drive vehicle. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
7. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminals No. 1 and 2. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EGR vacuum regulator solenoid valve. Voltage tester should flash. If voltage tester lights up constantly or does not flash, go to next step. If voltage tester flashes, circuit is okay. Erase DTC memory and test drive vehicle.
8. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
9. If voltage tester had lit up constantly, go to step 12). If voltage tester did not flash, using DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 11).
10. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
11. Using DVOM, check for short to B+ between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
12. Using DVOM, check for a short to ground between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1402/17810 - EGR VALVE CIRCUIT SHORT TO B+

Note. DTC is set with engine speed 1000-3500 RPM, engine load 33-66 percent, EGR valve duty cycle more than 30 percent when PCM output of EGR valve is high for more than 1.2 seconds.

1. Inspect EGR vacuum regulator solenoid valve connector for looseness and/or corrosion. EGR vacuum regulator solenoid valve is located in center rear of engine compartment. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect EGR vacuum regulator solenoid valve electrical connector. Using a DVOM, measure resistance between EGR vacuum regulator solenoid valve terminals. Resistance should be 25-35 ohms. If resistance is to specification, go to next step. If resistance is not to specification, replace EGR vacuum regulator solenoid valve. Erase DTC memory and test drive vehicle.
3. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light. If voltage tester does not light, go to next step. If voltage tester lights, go to step 7).
4. Check fuse for EGR vacuum regulator solenoid valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
5. Using a DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Repair fuel pump relay circuit or replace fuel pump relay as necessary. Erase DTC memory and test drive vehicle. If fuel pump relay triggering is okay, go to next step.
6. Repair wiring as necessary. Erase DTC memory and test drive vehicle. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
7. With ignition on, connect VAG 1527B voltage tester between EGR vacuum regulator solenoid valve harness connector terminals No. 1 and 2. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EGR vacuum regulator solenoid valve. Voltage tester should flash. If voltage tester lights up constantly or does not flash, go to next step. If voltage tester flashes, circuit is okay. Erase DTC memory and test drive vehicle.
8. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
9. If voltage tester had lit up constantly, go to step 12). If voltage tester did not flash, using DVOM, check resistance between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 11).
10. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
11. Using DVOM, check for short to B+ between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
12. Using DVOM, check for a short to ground between EGR vacuum regulator solenoid valve harness connector terminal No. 2 and test box socket E1. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1407/17815 - EGR TEMPERATURE SENSOR SIGNAL TOO LOW

Note. DTC is set after a cold start (coolant temperature less than 86°F (30°C) as soon as EGR temperature sensor signal is received exceeding 392°F (200°C).

1. Inspect EGR temperature sensor for looseness and/or corrosion. EGR temperature sensor is located on intake manifold under throttle body. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect EGR temperature sensor electrical connector. Turn ignition on. Using a DVOM, measure voltage between EGR temperature sensor harness connector terminals. Voltage should be approximately 5 volts. If voltage is to specification, go to step 4). If voltage is not to specification, go to next step.
3. Repair open circuit between EGR temperature sensor harness connector terminal No. 1 and PCM connector "A" terminal No. 23, and/or between EGR temperature sensor harness connector terminal No. 2 and engine ground. Erase DTC memory and test drive vehicle.
4. Turn ignition off. Remove EGR temperature sensor from engine. Using a DVOM on 200 k/ohm scale, connect leads to EGR temperature sensor terminals. Immerse EGR temperature sensor in hot water 176-212°F (80-100°C). Observe DVOM reading. Resistance should change. If resistance changes, go to next step. If resistance does not change, replace EGR temperature sensor. Erase DTC memory and test drive vehicle.
5. EGR temperature sensor is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P1408/17816 - EGR TEMPERATURE SENSOR SIGNAL TOO HIGH

Note. DTC is set when EGR temperature sensor signal is less than 41°F (5°C) for more than 32 seconds with idle switch open, coolant temperature more than 162°F (72°C), throttle angle less than 42.5 degrees, vehicle speed 44-66 MPH, EGR valve duty cycle more than 50 percent, engine speed 1500-3300 RPM and engine load 16-60 percent.

1. Inspect EGR temperature sensor for looseness and/or corrosion. EGR temperature sensor is located on intake manifold under throttle body. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect EGR temperature sensor electrical connector. Turn ignition on. Using a DVOM, measure voltage between EGR temperature sensor harness connector terminals. Voltage should be approximately 5 volts. If voltage is to specification, go to step 4). If voltage is not to specification, go to next step.
3. Repair open circuit between EGR temperature sensor harness connector terminal No. 1 and PCM connector "A" terminal No. 23, and/or between EGR temperature sensor harness connector terminal No. 2 and engine ground. Erase DTC memory and test drive vehicle.
4. Turn ignition off. Remove EGR temperature sensor from engine. Using a DVOM on 200 k/ohm scale, connect leads to EGR temperature sensor terminals. Immerse EGR temperature sensor in hot water 176-212°F (80-100°C). Observe DVOM reading. Resistance should change. If resistance changes, go to next step. If resistance does not change, replace EGR temperature sensor. Erase DTC memory and test drive vehicle.
5. EGR temperature sensor is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.

DTC P1409/17817 - FUEL TANK VENTILATION VALVE ELEC MALFNCTION

Note. DTC is set when evaporative emission valve control module output is low for more than 1.2 seconds with engine speed less than 1100 RPM, engine load less than 33 percent and evaporative emissions valve duty cycle is more than 25 percent.

1. Inspect EVAP canister purge regulator valve connector for looseness and/or corrosion. EVAP canister purge regulator valve is located in right front corner of engine compartment. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect EVAP canister purge valve electrical connector. Using DVOM, check EVAP canister purge valve resistance. Measure resistance across EVAP canister purge valve terminals. Resistance should be 20-28 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace EVAP canister purge valve. Erase DTC memory and test drive vehicle.
3. With ignition on, connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for EVAP canister purge valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
4. Using a DVOM, check wiring between EVAP canister purge valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
5. Connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EVAP canister purge valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, ensure EVAP canister purge valve is not mechanically binding. Replace as necessary. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. If voltage tester had lit up constantly, go to step 10). If voltage tester did not flash, using DVOM, check resistance between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 9).
8. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
9. Using DVOM, check for short to B+ between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
10. Using DVOM, check for a short to ground between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1410/17818 - FUEL TANK VENTILATION VALVE SHORT TO B+

Note. DTC is set when evaporative emission valve control module output is high for more than 1.2 seconds with engine speed more than 1250 RPM, engine load more than 40 percent and evaporative emissions valve duty cycle is less than 19 percent.

1. Inspect EVAP canister purge regulator valve connector for looseness and/or corrosion. EVAP canister purge regulator valve is located in right front corner of engine compartment. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect EVAP canister purge valve electrical connector. Using DVOM, check EVAP canister purge valve resistance. Measure resistance across EVAP canister purge valve terminals. Resistance should be 20-28 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace EVAP canister purge valve. Erase DTC memory and test drive vehicle.
3. With ignition on, connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for EVAP canister purge valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
4. Using a DVOM, check wiring between EVAP canister purge valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
5. Connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EVAP canister purge valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, ensure EVAP canister purge valve is not mechanically binding. Replace as necessary. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. If voltage tester had lit up constantly, go to step 10). If voltage tester did not flash, using DVOM, check resistance between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 9).
8. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
9. Using DVOM, check for short to B+ between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
10. Using DVOM, check for a short to ground between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1500/17908 - FUEL PUMP RELAY CIRCUIT ELEC MALFUNCTION

Note. DTC is set only when P1201/17609, P1202/17610, P1203/17611, P1204/17612, P1205/17613 and P1206/17614 are stored simultaneously.

Check fuel pump relay and relay triggering. See SYSTEM/COMPONENT TESTS article. If fuel pump relay and relay triggering are okay, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1504/17912 - INTAKE AIR SYSTEM BYPASS AIR DETERMINED

Note. When DTC is set, both power output stages (positive and negative output) are switched off. IAC valve has no power and opens limp-home cross section.

1. Inspect air intake system for a leak. Repair as necessary. If an intake leak was not found, go to next step. If an intake leak was repaired, erase DTC memory and test drive vehicle.
2. Disconnect Idle Air Control (IAC) valve electrical connector. IAC valve is located on top right rear corner of engine. Using DVOM, check IAC valve resistance. Measure resistance across IAC valve terminals. Resistance should be 7-11 ohms. At room temperature, resistance will be lower. If resistance is measured at underhood operating temperatures, resistance will be higher. Go to next step.
3. If resistance is within specification, go to next step. If resistance is not with specification, replace IAC valve. Erase DTC memory and test drive vehicle.
4. Remove IAC valve from engine. Visually inspect surface of rotary slide for signs of wear and/or damage. DO NOT pry on rotary slide to check for ease of movement. Rotary slide could become damaged (scratched). If rotary slide is not visibly damaged, go to next step. If rotary slide is visibly damaged, replace IAC valve. Erase DTC memory and test drive vehicle.
5. With IAC valve still off of the engine, reconnect IAC valve electrical connector. Turn ignition on. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Check if rotary slide moves freely from stop to stop. If IAC valve does not react to triggering, go to next step. If rotary slide does not move freely (sticks, moves slowly or does not move fully in either direction), replace IAC valve. Erase DTC memory and test drive vehicle. If rotary slide moves freely from stop to stop, IAC valve is functioning properly. Go to step 11).
6. With IAC valve connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between IAC valve connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Voltage tester should flash. If voltage tester does not flash as specified, go to step 8). If voltage tester flashes as specified, go to next step.
7. With IAC valve connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between IAC valve connector terminal No. 2 and battery voltage. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Voltage tester should light. If voltage tester does not light, go to step 8). If voltage tester lights, circuits are functioning properly. Go to step 11).
8. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
9. Using DVOM, check continuity between IAC valve harness connector terminal No. 1 and test box socket D11, then between terminal No. 2 and test box socket D9. Continuity should be present. If continuity is not present on either or both circuits, repair wiring harness as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
10. If continuity is present but triggering still does not occur, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If triggering signal and wiring are okay, but IAC valve still does not react, replace IAC valve. Erase DTC memory and test drive vehicle.
11. Inspect throttle body assembly for mechanical damage. Replace throttle body assembly as necessary. Erase DTC memory and test drive vehicle. If throttle body assembly is okay, erase DTC memory and test drive vehicle.

DTC P1505/17913 - CTP SWITCH DOES NOT CLOSE (OPEN CIRCUIT)

Note. DTC is set when idle switch has not been recognized as closed even once after 500 RPM has been exceeded, with a trip of at least 20 minutes, with speeds under 63 MPH.

1. Check floor mat near accelerator pedal. Make sure floor mat is not pressing on accelerator pedal. If floor mat is not pressing on accelerator pedal, go to next step. If floor mat is pressing on accelerator pedal, reposition floor mat as necessary. Erase DTC memory and test drive vehicle.
2. Ensure accelerator pedal cable is properly adjusted. See «ADJUSTMENTS»(/audi/a4/b5-1994-1999/remont/adjustments/#engine-controls-adjustments) article. If accelerator pedal cable adjustment was okay, go to next step. If accelerator pedal cable was adjusted, erase DTC memory and test drive vehicle.
3. Inspect Throttle Position (TP) sensor connector for looseness and/or corrosion. CTS switch is located within Throttle Position (TP) sensor. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
4. With ignition off, remove air intake sound absorber. Disconnect TP sensor connector. Using a DVOM, check continuity between TP sensor terminals No. 4 and 6.
5. Continuity should be present. Open throttle slightly. DVOM should show infinity (no continuity). If continuity readings are not as specified, adjust TP sensor. See CLOSED THROTTLE POSITION (CTP) SWITCH in «ADJUSTMENTS»(/audi/a4/b5-1994-1999/remont/adjustments/#engine-controls-adjustments) article. After adjusting TP sensor, if continuity readings are as specified, go to step 7).
6. If after adjusting TP sensor, continuity readings are not as specified, replace TP sensor. Erase DTC memory and test drive vehicle.
7. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
8. Using DVOM, check resistance between TP sensor terminal No. 4 (ground) and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
9. Using DVOM, check resistance between TP sensor terminal No. 6 (signal) and test box socket A4. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
10. Inspect throttle body assembly for mechanical damage. Replace throttle body assembly as necessary. Erase DTC memory and test drive vehicle. If throttle body assembly is okay, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1506/17914 - CTP SWITCH DOES NOT OPEN (SHORT TO GROUND)

Note. DTC is set when idle switch is closed for more than 3 seconds with throttle opening more than 7 degrees.

1. Inspect Closed Throttle Position (CTP) switch connector for looseness and/or corrosion. CTS switch is located within Throttle Position (TP) sensor. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. With ignition off, remove air intake sound absorber. Disconnect TP sensor connector. Using a DVOM, check continuity between TP sensor terminals No. 4 and 6.
3. Continuity should be present. Open throttle slightly. DVOM should show infinity (no continuity). If continuity readings are not as specified, adjust TP sensor. See CLOSED THROTTLE POSITION (CTP) SWITCH in «ADJUSTMENTS»(/audi/a4/b5-1994-1999/remont/adjustments/#engine-controls-adjustments) article. After adjusting TP sensor, if continuity readings are as specified, go to step 5).
4. If after adjusting TP sensor, continuity readings are not as specified, replace TP sensor. Erase DTC memory and test drive vehicle.
5. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check resistance between TP sensor terminal No. 4 (ground) and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
7. Using DVOM, check resistance between TP sensor terminal No. 6 (signal) and test box socket A4. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
8. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1509/17917 - IAC CIRCUIT ELECTRICAL MALFUNCTION

Note. When DTC is set, both power output stages (positive and negative output) are switched off. IAC valve has no power and opens limp-home cross section.

1. Inspect Idle Air Control (IAC) valve connector for looseness and/or corrosion. IAC valve is located on top right rear corner of engine. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect Idle Air Control (IAC) valve electrical connector. IAC valve is located on top right rear corner of engine. Using DVOM, check IAC valve resistance. Measure resistance across IAC valve terminals. Resistance should be 7-11 ohms. At room temperature, resistance will be lower. If resistance is measured at underhood operating temperatures, resistance will be higher. Go to next step.
3. If resistance is within specification, go to next step. If resistance is not with specification, replace IAC valve. Erase DTC memory and test drive vehicle.
4. Remove IAC valve from engine. Visually inspect surface of rotary slide for signs of wear and/or damage. DO NOT pry on rotary slide to check for ease of movement. Rotary slide could become damaged (scratched). If rotary slide is not visibly damaged, go to next step. If rotary slide is visibly damaged, replace IAC valve. Erase DTC memory and test drive vehicle.
5. With IAC valve still off of the engine, reconnect IAC valve electrical connector. Turn ignition on. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Check if rotary slide moves freely from stop to stop. If IAC valve does not react to triggering, go to next step. If rotary slide does not move freely (sticks, moves slowly or does not move fully in either direction), replace IAC valve. Erase DTC memory and test drive vehicle. If rotary slide moves freely from stop to stop, IAC valve is functioning properly. Replace faulty PCM. Erase DTC memory and test drive vehicle.
6. With IAC valve connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between IAC valve connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Voltage tester should flash. If voltage tester does not flash as specified, go to step 8). If voltage tester flashes as specified, go to next step.
7. With IAC valve connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between IAC valve connector terminal No. 2 and battery voltage. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Voltage tester should light. If voltage tester does not light, go to step 8). If voltage tester lights, circuits are functioning properly. Replace faulty PCM. Erase DTC memory and test drive vehicle.
8. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
9. Using DVOM, check continuity between IAC valve harness connector terminal No. 1 and test box socket D11, then between terminal No. 2 and test box socket D9. Continuity should be present. If continuity is not present on either or both circuits, repair wiring harness as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
10. If continuity is present but triggering still does not occur, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If triggering signal and wiring are okay, but IAC valve still does not react, replace IAC valve. Erase DTC memory and test drive vehicle.

DTC P1510/17918 - IAC CIRCUIT SHORT TO B+

Note. When DTC is set, both power output stages (positive and negative output) are switched off. IAC valve has no power and opens limp-home cross section.

1. Inspect Idle Air Control (IAC) valve connector for looseness and/or corrosion. IAC valve is located on top right rear corner of engine. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect Idle Air Control (IAC) valve electrical connector. IAC valve is located on top right rear corner of engine. Using DVOM, check IAC valve resistance. Measure resistance across IAC valve terminals. Resistance should be 7-11 ohms. At room temperature, resistance will be lower. If resistance is measured at underhood operating temperatures, resistance will be higher. Go to next step.
3. If resistance is within specification, go to next step. If resistance is not with specification, replace IAC valve. Erase DTC memory and test drive vehicle.
4. Remove IAC valve from engine. Visually inspect surface of rotary slide for signs of wear and/or damage. DO NOT pry on rotary slide to check for ease of movement. Rotary slide could become damaged (scratched). If rotary slide is not visibly damaged, go to next step. If rotary slide is visibly damaged, replace IAC valve. Erase DTC memory and test drive vehicle.
5. With IAC valve still off of the engine, reconnect IAC valve electrical connector. Turn ignition on. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Check if rotary slide moves freely from stop to stop. If IAC valve does not react to triggering, go to next step. If rotary slide does not move freely (sticks, moves slowly or does not move fully in either direction), replace IAC valve. Erase DTC memory and test drive vehicle. If rotary slide moves freely from stop to stop, IAC valve is functioning properly. Replace faulty PCM. Erase DTC memory and test drive vehicle.
6. With IAC valve connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between IAC valve connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Voltage tester should flash. If voltage tester does not flash as specified, go to step 8). If voltage tester flashes as specified, go to next step.
7. With IAC valve connector connected, push back rubber boot on connector. Connect VAG 1527B voltage tester between IAC valve connector terminal No. 2 and battery voltage. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger IAC valve. Voltage tester should light. If voltage tester does not light, go to step 8). If voltage tester lights, circuits are functioning properly. Replace faulty PCM. Erase DTC memory and test drive vehicle.
8. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
9. Using DVOM, check continuity between IAC valve harness connector terminal No. 1 and test box socket D11, then between terminal No. 2 and test box socket D9. Continuity should be present. If continuity is not present on either or both circuits, repair wiring harness as necessary. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. Erase DTC memory and test drive vehicle.
10. If continuity is present but triggering still does not occur, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If triggering signal and wiring are okay, but IAC valve still does not react, replace IAC valve. Erase DTC memory and test drive vehicle.

DTC P1511/17919 - INTAKE MANIFOLD CHANGE-OVER VALVE CIRCUIT ELECTRICAL MALFUNCTION

1. Inspect intake manifold change-over valve connector for looseness and/or corrosion. Intake manifold change-over valve is located under mass airflow sensor. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect intake manifold change-over valve electrical connector. Using DVOM, check valve resistance. Measure resistance across valve terminals. Resistance should be 25-35 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace intake manifold change-over valve. Erase DTC memory and test drive vehicle.
3. With ignition on, connect VAG 1527B voltage tester between intake manifold change-over valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for intake manifold change-over valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
4. Using a DVOM, check wiring between intake manifold change-over valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
5. Connect VAG 1527B voltage tester between intake manifold change-over valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger intake manifold change-over valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. If voltage tester had lit up constantly, go to step 10). If voltage tester did not flash, using DVOM, check resistance between intake manifold change-over valve harness connector terminal No. 2 and test box socket B4. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 9).
8. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
9. Using DVOM, check for short to B+ between intake manifold change-over valve harness connector terminal No. 2 and test box socket B4. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
10. Using DVOM, check for a short to ground between intake manifold change-over valve harness connector terminal No. 2 and test box socket B4. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1512/17920 - INTAKE MANIFOLD CHANGE-OVER VALVE CIRCUIT SHORT TO B+

1. Inspect intake manifold change-over valve connector for looseness and/or corrosion. Intake manifold change-over valve is located under mass airflow sensor. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
2. Disconnect intake manifold change-over valve electrical connector. Using DVOM, check valve resistance. Measure resistance across valve terminals. Resistance should be 25-35 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace intake manifold change-over valve. Erase DTC memory and test drive vehicle.
3. With ignition on, connect VAG 1527B voltage tester between intake manifold change-over valve harness connector terminal No. 1 and ground. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger fuel pump relay. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for intake manifold change-over valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
4. Using a DVOM, check wiring between intake manifold change-over valve harness connector terminal No. 1 and fuse. See «WIRING DIAGRAMS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l) section. If wiring is okay, check fuel pump relay and relay triggering. See «SYSTEM/COMPONENT TESTS»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article. Go to next step.
5. Connect VAG 1527B voltage tester between intake manifold change-over valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger intake manifold change-over valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, circuit is okay. Erase DTC memory and test drive vehicle.
6. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
7. If voltage tester had lit up constantly, go to step 10). If voltage tester did not flash, using DVOM, check resistance between intake manifold change-over valve harness connector terminal No. 2 and test box socket B4. Maximum resistance is one ohm. If resistance is not within specification, go to next step. If resistance is within specification, circuit resistance is okay. Go to step 9).
8. Repair open circuit as necessary. Erase DTC memory and test drive vehicle. If open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
9. Using DVOM, check for short to B+ between intake manifold change-over valve harness connector terminal No. 2 and test box socket B4. If short to B+ is present, repair as necessary. Erase DTC memory and test drive vehicle. If short to B+ cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) in this article.
10. Using DVOM, check for a short to ground between intake manifold change-over valve harness connector terminal No. 2 and test box socket B4. If a short to ground is not present, circuit is okay. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If a short to ground is present, repair as necessary. Erase DTC memory and test drive vehicle.

DTC P1600/18008 - POWER SUPPLY (B+) TERMINAL 15 LOW VOLTAGE

Note. If DTC is set sporadically, disregard DTC. This DTC can set if engine idles for a long time with a lot of electrical accessories turned on when battery is quite discharged. DTC sets when supply voltage is less than 10.08 volts for more than one second (PCM will not operate when voltage is less than 6.5 volts).

1. Inspect battery for proper charge. Charge or replace battery as necessary. If battery charge is okay, go to next step. If battery was charged or replaced, erase DTC memory and test drive vehicle.
2. Check PCM voltage and ground circuits. See PCM VOLTAGE & GROUND CHECK in this article. Repair circuits as necessary. If circuits are okay, go to next step. If circuits were repaired, erase DTC memory and test drive vehicle.
3. Inspect electrical system for excessive current draw with ignition off. Repair circuits as necessary. If circuits are okay, go to next step. If circuits were repaired, erase DTC memory and test drive vehicle.
4. Inspect generator for malfunction. Repair or replace generator as necessary. If generator is okay, go to next step. If generator was repaired or replaced, erase DTC memory and test drive vehicle.

DTC P1602/18010 - POWER SUPPLY (B+) TERMINAL 30 LOW VOLTAGE

1. DTC is set when battery or PCM is disconnected with ignition on or an attempt to start engine was made with ignition power output stage disconnected. Go to next step.
2. If DTC was set because of conditions identified in step 1), DTC will clear itself after second engine start. See «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again. If DTC did not set because of conditions identified in step 1), go to next step.
3. Check ground connection between battery and vehicle body. Repair as necessary. If ground connections are okay, go to next step. If ground connections were repaired, erase DTC memory and test drive vehicle.
4. Check for an open circuit between battery and PCM connectors. Repair as necessary. See «PCM VOLTAGE & GROUND CHECK»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-voltage-ground-check) in this article. Repair circuits as necessary. Erase DTC memory and test drive vehicle.

DTC P1606/18014 - ROUGH ROAD/ACCEL SENSOR ELEC MALFUNCTION

Note. If rough road is recognized by Anti-Lock Brake System (ABS) control module, combustion misfiring recognition in PCM is switched off by ABS control module.

1. If an emissions test was run in which only front wheels moved and rear wheels remained stationary, this DTC will set. Go to next step. If an emissions test was not run in which only front wheels moved and rear wheels remained stationary, go to step 3).
2. During an emissions test, fuse must be removed from ABS control module. After emissions test, erase DTC memory for PCM and ABS control module and test drive vehicle.
3. Check for DTCs stored in ABS control module. If no DTCs are stored in ABS control module, go to next step. If DTCs are stored in ABS control module, DTC P1606/18014 will be set in PCM. Check DTCs stored in ABS control module and repair as necessary. Erase DTC memory and test drive vehicle. NOTE: Step 4) is for information only.
4. If road wheel malfunctions occur, a combustion misfire DTC may result. If ABS control module recognizes a free turning wheel, a rough road signal is generated. If PCM recognizes a rough road signal, misfire recognition is turned off by the PCM. Rough road signal is monitored by PCM. Go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
6. Using DVOM, check rough road signal wire between PCM and ABS control module for an open or short circuit. Repair circuit as necessary. If circuit is okay, go to next step. If circuit was repaired, erase DTC memory and test drive vehicle.
7. Replace ABS control module. Erase DTC memory and test drive vehicle. If DTC sets again, go to next step.
8. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.

DTC P1611/18019 - MALFUNCTION INDICATOR LIGHT (MIL) CALL-UP/TRANSMISSION CONTROL MODULE (TCM) SHORT TO GROUND

Note. This DTC can only occur if vehicle is equipped with an automatic transmission. If malfunctions are recognized that are related to exhaust system, the automatic transmission switches on MIL.

1. Using DVOM, check MIL circuit between PCM and TCM for a short circuit. Repair circuit as necessary. If circuit is okay, go to next step. If circuit was repaired, erase DTC memory and test drive vehicle.
2. Replace faulty TCM. Erase DTC memory and test drive vehicle. If DTC sets again, go to next step.
3. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

DTC P1612/18020 - PCM INCORRECTLY CODED

1. If DTC P1606/18014 is not also set in memory, go to next step. If DTC P1606/18014 is also set in memory, PCM is incorrectly coded. Vehicle is equipped with traction control, but PCM coding was done for a vehicle without traction control. Properly code PCM test drive vehicle. See «PCM CODING»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__pcm-coding) and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, go to next step.
2. PCM is incorrectly coded. Vehicle is equipped with an automatic transmission, but PCM coding was done for a vehicle with a manual transmission. Properly code PCM test drive vehicle. See PCM CODING and «TEST DRIVE»(/audi/a4/b5-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-28l__test-drive) in this article. Recheck DTC memory and verify DTC does not set again.

DTC P1613/18021 - MALFUNCTION INDICATOR LIGHT (MIL) CALL-UP CIRCUIT OPEN OR SHORT TO B+

Note. This DTC can only occur if vehicle is equipped with an automatic transmission. If malfunctions are recognized that are related to exhaust system, the automatic transmission switches on MIL.

1. Using DVOM, check MIL circuit between PCM and TCM for a short circuit. Repair circuit as necessary. If circuit is okay, go to next step. If circuit was repaired, erase DTC memory and test drive vehicle.
2. Replace faulty TCM. Erase DTC memory and test drive vehicle. If DTC sets again, go to next step.
3. Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.

SUMMARY

If no hard codes (or pass codes only) are present, driveability symptoms exist or intermittent codes exist, proceed to the TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

Wiring Diagram (A4 2.8L - 1 Of 2). Scheme 15

Wiring Diagram (A4 2.8L - 2 Of 2). Scheme 16

See also:
• TESTS W/O CODES
• AUDI TYPE 01V ELECTRONIC CONTROLS & OVERHAUL
• ADJUSTMENTS
• SYSTEM/COMPONENT TESTS
• BASIC TESTING
• RETRIEVING CODES
• DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
• PCM VOLTAGE & GROUND CHECK
• CLEARING CODES
• P0102
• P0103
• P0116
• P0117
• P0118
• P0120
• P0121
• P0122
• P0123
• P0130
• P0132
• P0133
• P0134
• P0135
• P0136
• P0138
• P0141
• P0150
• P0152
• P0153
• P0154
• P0155
• P0156
• P0158
• P0161
• P0170
• P0171
• P0172
• P0173
• P0174
• P0175
• P0300
• P0301
• P0302
• P0303
• P0304
• P0305
• P0306
• P0322
• P0327
• P0332
• P0337
• P0401
• P0402
• P0422
• P0432
• P0440
• P0452
• P0453
• P0461
• P0501
• P0605
• P0706
• P0707
• P1101
• P1102
• P1104
• P1105
• P1106
• P1107
• P1109
• P1110
• P1201
• P1202
• P1203
• P1204
• P1205
• P1206
• P1213
• P1214
• P1215
• P1216
• P1217
• P1218
• P1250
• P1325
• P1326
• P1327
• P1328
• P1329
• P1330
• P1339
• P1340
• P1341
• P1343
• P1345
• P1391
• P1392
• P1393
• P1394
• P1395
• P1396
• P1400
• P1402
• P1407
• P1408
• P1409
• P1410
• P1500
• P1504
• P1505
• P1506
• P1509
• P1510
• P1511
• P1512
• P1600
• P1602
• P1606
• P1611
• P1612
• P1613
• PCM CODING
• TEST DRIVE