Multiport Fuel Injection (mfi), Generic Scan Tool (2.8l v6 Aha, Atq) Audi A6 C5

Component locations, overview

The following components are not displayed in the installation overview

Malfunction Indicator Lamp (MIL) -K83

1. Checking, see «MALFUNCTION INDICATOR LAMP (MIL) IN INSTRUMENT CLUSTER, CHECKING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Electronic Power Control (EPC) Warning Lamp -K132

1. Vehicles with engine code ATQ
2. Checking, see «ELECTRONIC POWER CONTROL (EPC) WARNING LAMP IN INSTRUMENT CLUSTER, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#fuel-supply-generic-scan-tool-28l-v6-aha-atq) .

Leak detection pump (LDP) -V144

1. Under wheel housing liner in rear left wheelhousing
2. Checking, see «LEAK DETECTION PUMP (LDP), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#fuel-supply-generic-scan-tool-28l-v6-aha-atq) .

Throttle Position (TP) Sensor -G79

1. Vehicles with engine code ATQ
2. Checking, see «THROTTLE POSITION (TP) SENSOR, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#fuel-supply-generic-scan-tool-28l-v6-aha-atq)

Clutch Vacuum Vent Valve Switch -F36

1. Vehicles with engine code ATQ
2. Checking, see «SIGNAL FROM CLUTCH VACUUM VENT VALVE SWITCH, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq)

Secondary Air Injection (AIR) Pump Relay -J299

1. Component location, see «SECONDARY AIR SYSTEM, CHECKING FOR PROPER SEAL»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq)

Secondary Air Injection (AIR) Pump Motor -V101

1. Checking, see «SECONDARY AIR INJECTION (AIR) PUMP MOTOR, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq)

The following components are displayed in the Component location overview

Note. Cylinder bank 1 is located on right side in direction of travel. Cylinder bank 2 is located on left side in direction of travel.

Note. The following list refers to items in (Scheme 624).

1. 4-pin harness connector green for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S) Heater 1 (behind Three Way Catalytic Converter (TWC)) - Z29-, cylinder bank 1
2. 4-pin harness connector brown for Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- and Oxygen Sensor (O2S) Heater 2 (behind Three Way Catalytic Converter (TWC)) - Z30-, cylinder bank 2
3. 4-pin harness connector Black for Heated Oxygen Sensor (HO2S) -G39- before catalytic converter and Oxygen Sensor (O2S) Heater -Z19-, cylinder bank 1
4. 3-pin harness connector Vehicles with engine code AHA: blue Vehicles with engine code ATQ: brown for Knock Sensor (KS) 1 -G61-, cylinder bank 1
5. Engine Coolant Temperature (ECT) Sensor -G62
6. Secondary Air Injection (AIR) Solenoid Valve -N112 - Checking, see «SECONDARY AIR INJECTION (AIR) VALVE, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__secondary-air-injection-air-valve-checking)
7. Intake Air Temperature (IAT) Sensor -G42
8. Intake Manifold Change -Over Valve -N156
9. Throttle Valve Control Module - J338- Heated by coolant
10. 4-pin harness connector Black for Heated Oxygen Sensor (HO2S) 2 -G108- and Oxygen Sensor (O2S) Heater 2 -Z28-, cylinder bank 2
11. 3-pin harness connector Vehicles with engine code AHA: blue Vehicles with engine code ATQ: brown for Knock Sensor (KS) 2 -G66-, cylinder bank 2
12. 3-pin harness connector gray for Engine Speed (RPM) Sensor - G28
13. Engine Control Module (ECM) (Motronic Engine Control Module (ECM) -J220-) Component location: in protective housing, plenum chamber, left
14. Fuel pressure regulator
15. Camshaft Position (CMP) Sensor 2 -G163- Cylinder bank 2 See «IGNITION, SERVICING»(/audi/a6/c5-1997-2001/remont/ignition-system/#ignitionglow-plug-system-generic-scan-tool-28l-v6-aha-atq) .
16. Heated Oxygen Sensor (HO2S) 2 - G108- bank 1 before catalytic converter, 50 Nm
17. Engine Speed (RPM) Sensor -G28
18. Knock Sensor (KS) 2 -G66- Cylinder bank 2 See «IGNITION, SERVICING»(/audi/a6/c5-1997-2001/remont/ignition-system/#ignitionglow-plug-system-generic-scan-tool-28l-v6-aha-atq) .
19. Valve -2- for camshaft adjustment - N208 - Cylinder bank 2 See «IGNITION, SERVICING»(/audi/a6/c5-1997-2001/remont/ignition-system/#ignitionglow-plug-system-generic-scan-tool-28l-v6-aha-atq) .
20. Ignition Coil -N152- with power output stage See «IGNITION, SERVICING»(/audi/a6/c5-1997-2001/remont/ignition-system/#ignitionglow-plug-system-generic-scan-tool-28l-v6-aha-atq) .
21. Knock Sensor (KS) 1 -G61- Cylinder bank 1 See «IGNITION, SERVICING»(/audi/a6/c5-1997-2001/remont/ignition-system/#ignitionglow-plug-system-generic-scan-tool-28l-v6-aha-atq) .
22. Cylinder 1 Fuel Injector -N30- to Cylinder 4 Fuel Injector -N33-, Cylinder 5 Fuel Injector -N83-, Cylinder 6 Fuel Injector -N84
23. Camshaft Position (CMP) sensor - G40- Cylinder bank 1 See «IGNITION, SERVICING»(/audi/a6/c5-1997-2001/remont/ignition-system/#ignitionglow-plug-system-generic-scan-tool-28l-v6-aha-atq) .
24. Ground connection on the engine bracket, right
25. Heated Oxygen Sensor (HO2S) - G39- bank 1 before catalytic converter, 50 Nm
26. Valve -1- for camshaft adjustment - N205 - Cylinder bank 1 See «IGNITION, SERVICING»(/audi/a6/c5-1997-2001/remont/ignition-system/#ignitionglow-plug-system-generic-scan-tool-28l-v6-aha-atq) .
27. Secondary Air Injection (AIR) Pump Motor -V101- Checking, see «SECONDARY AIR INJECTION (AIR) PUMP MOTOR, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq)
28. Mass Air Flow (MAF) Sensor -G70
29. Evaporative Emission (EVAP) Canister Purge Regulator Valve - N80- at air filter housing Installation position: Arrow points in direction of flow Checking, see «EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR VALVE, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#fuel-supply-generic-scan-tool-28l-v6-aha-atq__evaporative-emission-evap-canister-purge-regulator)

Identifying Fuel Injection And Ignition System Components Locations. Scheme 624

Fuel Injection, general notes

Servicing ignition, see IGNITION/GLOW PLUG SYSTEM, GENERIC SCAN TOOL - 2.8L V6 AHA, ATQ .

Note. The Engine Control Module (ECM) is equipped with an On Board Diagnostic (OBD) Always check DTC memory first, before performing repairs or troubleshooting. Vacuum hoses and connections should also be checked (unmetered air). For the electric components to work properly, a voltage of at least 11.5 V is required. Do not use any silicone sealant. Traces of silicone components which are sucked into the engine are not burned there, and they damage the oxygen sensor. The battery must only be disconnected and connected with the ignition switched off, since the Engine Control Module (ECM) can otherwise be damaged. Fuel hoses at engine must only be secured with spring-type clamps. The use of clamping collars or screw clamps is not permitted. see scheme 2: Identifying VAS5024A Spring Clip Installation Tool VAS5024A spring clip installation tool is recommended for installing spring-type clips. Components marked with * are tested via On Board Diagnostic (OBD). See DIAGNOSTIC MODE 3: CHECK DTC MEMORY. It is possible that the control module will recognize a malfunction and store a DTC during some tests. Therefore the following work steps must be performed in the mentioned sequence after ending all tests and repairs. - Check DTC memory. See DIAGNOSTIC MODE 3: CHECK DTC MEMORY. - Erase DTC memory. See DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA. - For completion, generate readiness code. See READINESS CODE, GENERATING.

Safety precautions, see SAFETY PRECAUTIONS .

Rules of cleanliness, see RULES OF CLEANLINESS .

Technical data, see TECHNICAL DATA .

Fuel injection system, removing and installing parts

Note. Cylinder bank 1 is located on right side in direction of travel. Cylinder bank 2 is located on left side in direction of travel.

Note. The following list refers to items in (Scheme 625).

1. Air filter housing Disassembling and assembling, see «AIR FILTER, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__air-filter-disassembling-and-assembling)
2. 20 Nm
3. Mass Air Flow (MAF) Sensor -G70- * Checking, see «MASS AIR FLOW (MAF) SENSOR, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__mass-air-flow-maf-sensor-checking)
4. Seal Replace if damaged
5. Connection hose
6. Engine Control Module (ECM)* (Motronic Engine Control Module (ECM) -J220-) Component location: in protective housing, plenum chamber, left Engine code AHA: 80 -pin Engine code ATQ: 121 -pin Checking voltage supply, see «VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE (ECM), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) Always replace, see «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing)
7. Mounting bracket
8. Connector Engine code AHA: 28 -pin Engine code ATQ: 40 -pin Switch ignition off before disconnecting or connecting connector disengage to pull off
9. Connector Engine code AHA: 52 -pin Engine code ATQ: 81 -pin Switch ignition off before disconnecting or connecting connector disengage to pull off
10. Intake air scoop
11. Connector black, 2 -pin For Intake Air Temperature (IAT) Sensor -G42
12. 10 Nm
13. to crankcase breather valve
14. 4-pin harness connector brown for Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- and Oxygen Sensor (O2S) Heater 2 (behind Three Way Catalytic Converter (TWC)) - Z30-, cylinder bank 2 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
15. Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- bank 2*, 50 Nm Component location: in rear catalytic converter cylinder bank 2 Only use "G 052 112 A3" to grease thread; do not let "G 052 112 A3" get onto slit of oxygen sensor Voltage supply of oxygen sensor heater via Fuel Pump (FP) Relay - J17- Check oxygen sensor heater for Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR HEATER FOR OXYGEN SENSORS BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-heater-for-oxygen-sensors) . Check Oxygen Sensor (O2S) and oxygen sensor control behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR AND OXYGEN SENSOR CONTROL BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-and-oxygen-sensor-control) .
16. Connector black, 2 -pin for Cylinder 1 Fuel Injector -N30- to Cylinder 4 Fuel Injector -N33-, Cylinder 5 Fuel Injector -N83-, Cylinder 6 Fuel Injector -N84
17. 4-pin harness connector Black for Heated Oxygen Sensor (HO2S) 2 -G108- and Oxygen Sensor (O2S) Heater 2 -Z28-, cylinder bank 2 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
18. Heated Oxygen Sensor (HO2S) 2 -G108- bank 1*, 50 Nm Component location: in front exhaust pipe cylinder bank 2 Only use "G 052 112 A3" to grease thread; do not let "G 052 112 A3" get onto slit of oxygen sensor Voltage supply of oxygen sensor heater via Fuel Pump (FP) Relay - J17- Check oxygen sensor heater for Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC). See «COMPONENTS, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) . Check Oxygen Sensor (O2S) and oxygen sensor control before Three Way Catalytic Converter (TWC). See «FUNCTION TESTS»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .
19. To vacuum reservoir
20. Engine Speed (RPM) Sensor -G28-* in transmission housing above the starter ring gear Checking, see «ENGINE SPEED (RPM) SENSOR -G28-, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq)
21. 3-pin harness connector gray for engine speed (RPM) sensor Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
22. O-ring Replace if damaged
23. Spacer
24. Gasket Replace if damaged
25. Intake manifold Parts of the intake manifold change-over, removing and installing, see «PARTS OF INTAKE MANIFOLD CHANGE - OVER, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__parts-of-intake-manifold-change) Throttle Valve Control Module, removing and installing, see «THROTTLE VALVE CONTROL MODULE, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__throttle-valve-control-module-removing-and)
26. Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- bank 1*, 50 Nm Component location: in rear catalytic converter cylinder bank 1 Only use "G 052 112 A3" to grease thread; do not let "G 052 112 A3" get onto slit of oxygen sensor Voltage supply of oxygen sensor heater via Fuel Pump (FP) Relay - J17- Check oxygen sensor heater for Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR HEATER FOR OXYGEN SENSORS BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-heater-for-oxygen-sensors) . Check Oxygen Sensor (O2S) and oxygen sensor control behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR AND OXYGEN SENSOR CONTROL BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-and-oxygen-sensor-control) .
27. Heated Oxygen Sensor (HO2S) - G39- bank 1*, 50 Nm Component location: in front exhaust pipe cylinder bank 1 Use "G5" to grease thread only; do not let "G5" get onto slits of oxygen sensor body Voltage supply of oxygen sensor heater via Fuel Pump (FP) Relay - J17- Check oxygen sensor heater for Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC). See «COMPONENTS, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) . Check Oxygen Sensor (O2S) and oxygen sensor control before Three Way Catalytic Converter (TWC). See «FUNCTION TESTS»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .
28. 4-pin harness connector Black for Heated Oxygen Sensor (HO2S) -G39- before catalytic converter and Oxygen Sensor (O2S) Heater -Z19-, cylinder bank 1 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
29. 4-pin harness connector green for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S) Heater 1 (behind Three Way Catalytic Converter (TWC)) - Z29-, cylinder bank 1 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
30. Fuel rail with fuel injectors Disassembling and assembling, see «FUEL RAIL WITH FUEL INJECTORS, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-rail-with-fuel-injectors-disassembling)
31. Supply line Black Check for secure fitting secure with spring type clamps All Wheel Drive (AWD) vehicles: from fuel filter Front Wheel Drive (FWD) vehicles: from fuel filter
32. Return line blue or with blue marking Check for secure fitting secure with spring type clamps All Wheel Drive (AWD) vehicles: To flange on Fuel Pump (FP) in fuel tank Front Wheel Drive (FWD) vehicles: To flange on Fuel Pump (FP) in fuel tank
33. Engine Coolant Temperature (ECT) Sensor -G62-* blue for Engine Control Module (ECM) with Engine Coolant Temperature (ECT) Sensor -G2- If necessary, release pressure in cooling system before removing Checking, see «ENGINE COOLANT TEMPERATURE (ECT) SENSOR, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq)
34. Connector blue, 4 -pin for Engine Coolant Temperature (ECT) Sensor -G62
35. Retaining clip Check for secure fitting
36. Connector green, 2 -pin for Secondary Air Injection (AIR) Solenoid Valve -N112
37. Connector blue, 2 -pin for Intake Manifold Change -Over Valve -N156

Exploded View Of Air Filter Housing And Intake Manifold Components. Scheme 625

Air filter, disassembling and assembling

Note. The following list refers to items in (Scheme 626).

1. Air ducts to lock carrier
2. Intake hose with elbow Check for secure fitting
3. O-ring Replace if damaged
4. Clip
5. Air filter, upper portion
6. Seal Replace if damaged
7. Mass Air Flow (MAF) Sensor -G70-* Checking, see «MASS AIR FLOW (MAF) SENSOR, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__mass-air-flow-maf-sensor-checking)
8. 10 Nm
9. Filter element
10. Spacer sleeve
11. Rubber grommet
12. Base plate
13. Air filter, lower portion
14. to Secondary Air Injection (AIR) Pump Motor -V101

Identifying Air Filter Components. Scheme 626

Fuel rail with fuel injectors, disassembling and assembling

Note. The following list refers to items in (Scheme 627).

1. Fuel distributor
2. to T-piece «THROTTLE VALVE CONTROL MODULE, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__throttle-valve-control-module-removing-and) , item no. 4
3. Retaining clip Check for secure fitting
4. O-ring Always replace
5. Fuel pressure regulator Checking, see «FUEL PRESSURE REGULATOR AND RESIDUAL PRESSURE, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-pressure-regulator-and-residual-pressure)
6. O-ring Always replace
7. Cylinder 1 Fuel Injector -N30- to Cylinder 4 Fuel Injector -N33-, Cylinder 5 Fuel Injector -N83-, Cylinder 6 Fuel Injector -N84-* Checking, see «FUEL INJECTORS, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq)
8. Retaining clip Make sure clip is correctly seated on fuel injector and fuel rail

Identifying Fuel Rail With Fuel Injectors. Scheme 627

Parts of intake manifold change - over, removing and installing

Vacuum hose setup (Scheme 630)and (Scheme 631)

Note. The following list refers to items in (Scheme 628).

1. Vacuum actuator
2. Compression spring
3. Vacuum hose From intake manifold, see «THROTTLE VALVE CONTROL MODULE, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__throttle-valve-control-module-removing-and) , item 6
4. Check -valve Installation position: blue side to Y - piece , item 8
5. to Secondary Air Injection (AIR) Solenoid Valve See «CONNECTING PIPE AND COMBINATION VALVES - ASSEMBLY OVERVIEW»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__connecting-pipe-and-combination-valves) , item no. 6
6. 6 Nm
7. Intake Manifold Change -Over Valve -N156
8. Y-piece
9. To fuel pressure regulator See «FUEL RAIL WITH FUEL INJECTORS, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-rail-with-fuel-injectors-disassembling) , item no. 5.
10. T-piece
11. 10 Nm
12. Securing plate
13. Rubber grommet
14. Spacer sleeve
15. Vacuum reservoir Component location: in left wheelhousing for intake manifold change-over at full throttle
16. Intake manifold
17. Washer conical side toward intake manifold
18. Seal Replace if damaged
19. change-over roller
20. Seal for change -over roller

Identifying Parts Of Intake Manifold Change-Over System. Scheme 628

Throttle valve control module, removing and installing

Note. The following list refers to items in (Scheme 629).

1. Intake manifold
2. To suction jet pump
3. To fuel pressure regulator See «FUEL RAIL WITH FUEL INJECTORS, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-rail-with-fuel-injectors-disassembling) , item no. 5.
4. T-piece
5. To check-valve See «PARTS OF INTAKE MANIFOLD CHANGE - OVER, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__parts-of-intake-manifold-change) , item no. 4.
6. Vacuum hose
7. O-ring Replace if damaged
8. Bracket for change -over roller
9. 6 Nm
10. Intake Air Temperature (IAT) Sensor -G42-* Checking, see «INTAKE AIR TEMPERATURE (IAT) SENSOR, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq)
11. Intake air scoop
12. 10 Nm
13. to crankcase breather valve
14. Seal Replace if damaged
15. 10 Nm with locking fluid (e.g.: D 000 600 A2) when installing
16. Throttle Valve Control Module - J338-* Heated by coolant Checking, see «THROTTLE VALVE CONTROL MODULE, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq)
17. To Evaporative Emission (EVAP) canister purge regulator valve In engine compartment at air filter
18. Seal Replace if damaged

Identifying Throttle Valve Control Module Components. Scheme 629

Vacuum connections (top view)

Note. The following list refers to items in (Scheme 630).

1. to vacuum actuator for intake manifold change -over
2. to combination valves
3. Secondary Air Injection (AIR) solenoid valve
4. to Secondary Air Injection (AIR) Solenoid Valve
5. to T-piece at intake manifold
6. Check-valve
7. Intake manifold change-over valve
8. to vacuum reservoir in left wheelhousing
9. from T-piece at intake manifold
10. Fuel pressure regulator

Engine Vacuum Connections - Top View. Scheme 630

Vacuum connections (rear view)

1. Fuel pressure regulator
2. to crankcase breather valve
3. Suction jet pump
4. T-piece
5. Check-valve
6. Intake air scoop
7. Crankcase breather valve

Locating Fuel Rail Mounting Bolts. Scheme 631

Safety precautions

To reduce the risk of personal injury and/or damage to the fuel injection and ignition system, always observe the following

1. Do not touch or disconnect ignition wires when engine is running or turning at starting RPM.
2. Only disconnect and reconnect wires for injection and ignition system, including test leads, when ignition is turned off. (Scheme 632): Disconnecting Connector From Ignition Coil -N152
3. To operate engine at starting RPM without starting, for example during the compression test, disconnect connector -1- from Ignition Coil -N152 - (-2-) and remove Fuel Pump (FP) fuse (28).

If special testing equipment is required during road test, note the following

1. Test equipment must always be secured to the rear seat and operated from there by a second person. If test and measuring equipment is operated from the passenger seat, the person seated there could be injured in the event of an accident involving deployment of the passenger-side airbag.

Rules of cleanliness

When working on the fuel supply or fuel injection systems, the following "5 rules of cleanliness" should be carefully observed

1. Thoroughly clean all connections and the surrounding area before disconnecting.
2. Place parts that have been removed on a clean surface and cover. Use lint-free cloths only!
3. Carefully cover over opened components or seal, if repairs are not performed immediately.
4. Only install clean components: Only unpack replacement parts immediately prior to installation. Do not use parts that have been stored loose (in tool boxes etc.)
5. When the system is open: Do not work with compressed air if it can be avoided. Do not move vehicle unless absolutely necessary.

Technical data

TECHNICAL DATA

Oxygen sensor heater for oxygen sensors before Three Way Catalytic Converter (TWC), checking

Note. When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.

Recommended special tools and equipment

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 632

1. The respective fuses of Heated Oxygen Sensor (HO2S) -G39- and Heated Oxygen Sensor (HO2S) 2 -G108- must be OK: (Scheme 633): Identifying Fuse Holder
2. Ignition switched off.

Scheme 633

Scheme 634

1. Disconnect 4-pin harness connector to the respective oxygen sensor: Heated Oxygen Sensor (HO2S) -G39-, bank 1, 4 -pin harness connector (black, arrow). (Scheme 634): Identifying Heated Oxygen Sensor (HO2S) -G39-, Bank 1, 4-Pin Harness Connector (Black) Heated Oxygen Sensor (HO2S) 2 -G108-, bank 2, 4 -pin harness connector (black, arrow). (Scheme 635): Identifying Heated Oxygen Sensor (HO2S) 2 -G108-, Bank 2, 4-Pin Harness Connector (Black)

Note. To reach this harness connector, remove coolant reservoir attachment screws and tilt coolant reservoir to the side. The coolant hoses remain connected. Bank 1 = Cylinder bank 1, in direction of travel, right Bank 2 = Cylinder bank 2, in direction of travel, left

Scheme 635

1. Measure resistance for sensor heater at connector to oxygen sensor terminal 1+2. Specified value: 0.0 to 19.9 ohms (Scheme 636): Identifying HO2S Connector Terminals (Engine Code AHA)

Scheme 636

1. Measure resistance for sensor heater at connector to oxygen sensor terminal 1+2. Specified value: max: 200ohm (Scheme 637): Identifying HO2S Connector Terminals (Engine Code ATQ)

Continuation for all vehicles

If specified value is not obtained

1. Replace the respective oxygen sensor: Heated Oxygen Sensor (HO2S) -G39-, bank 1. See «EXHAUST MANIFOLD, FRONT EXHAUST PIPE WITH THREE WAY CATALYTIC CONVERTER (TWC) AND ATTACHMENTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__exhaust-manifold-front-exhaust-pipe-with) , item 1. Heated Oxygen Sensor (HO2S) 2 -G108-, bank 2. See «MUFFLERS WITH MOUNTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) , item 15.
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If specified value is obtained

Scheme 637

1. Check Ground (GND) activation of the respective oxygen sensor heater.
2. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 638): Identifying HO2S Harness Connector Terminals
3. Check wires between test box and 4 -pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

Vehicles with engine code AHA

HO2S HEATER RESISTANCE REFERENCE DATA - ENGINE CODE AHA

Vehicles with engine code ATQ

HO2S HEATER RESISTANCE REFERENCE DATA - ENGINE CODE ATQ

1. Also check wires for short circuit to B+ and Ground (GND). Specified value: INFINITY ohm
2. Check wire between 4 -pin connector terminal 1 and Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

If no malfunctions are found in wires

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

Oxygen sensor heater for oxygen sensors behind Three Way Catalytic Converter (TWC), checking

Note. When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Test requirements

1. The respective fuses of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- must be OK
2. Ignition switched off.

Scheme 638

Scheme 639

1. Disconnect 4-pin harness connector to the respective oxygen sensor: Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, bank 1, 4 -pin harness connector (green) (arrow). see scheme 18: Identifying Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, Bank 1, 4-Pin Harness Connector (Green) Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, bank 2, 4 -pin harness connector (brown, arrow). see scheme 19: Identifying Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, Bank 2, 4-Pin Harness Connector (Brown)

Note. Bank 1 = Cylinder bank 1, in direction of travel, right Bank 2 = Cylinder bank 2, in direction of travel, left

Identifying HO2S Connector Terminals - Behind Three Way Catalytic Converter. Scheme 640

1. Measure resistance for sensor heater at connector to oxygen sensor terminal 1+2. Specified value: 0.0 to 19.9 ohm

Identifying HO2S Connector Terminals - Behind Three Way Catalytic Converter. Scheme 641

1. Measure resistance for sensor heater at connector to oxygen sensor terminal 1+2. Specified value: max: 200 ohm

If specified value is not obtained

1. Replace the respective oxygen sensor: Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, bank 1. See «MUFFLERS WITH MOUNTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) , item 4. Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, bank 2. See «MUFFLERS WITH MOUNTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) , item 11.
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If specified value is obtained

1. Check Ground (GND) activation of the respective oxygen sensor heater.
2. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 642): Identifying HO2S Harness Connector Terminals - Behind Three Way Catalytic Converter
3. Check wires between test box and 4 -pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram. Wire resistance: max: 1.5ohm

HO2S (BEHIND TWC) HEATER RESISTANCE REFERENCE DATA - ENGINE CODE AHA

HO2S (BEHIND TWC) HEATER RESISTANCE REFERENCE DATA - ENGINE CODE ATQ

1. Also check wires for short circuit to B+ and Ground (GND). Specified value: INFINITY ohm
2. Check wire between 4 -pin connector terminal 1 and Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram. Wire resistance: max: 1.5ohm

If no malfunctions are found in wires

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

Mass Air Flow (MAF) sensor, checking

Note. Use only gold -plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) sensor.

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

1. The respective fuses of Mass Air Flow (MAF) Sensor -G70- must be OK: (Scheme 643): Identifying Fuse Holder
2. Fuel Pump (FP) Relay -J17- must be OK, check
3. Battery voltage must be at least 11.5 volts.
4. All electrical consumers like, for example, lights and rear window heating must be switched off.
5. Parking brake must be engaged or else daylight driving lights will be switched on.
6. If vehicle is equipped with an A/C system, it must be switched off.
7. Ground (GND) connections between engine and chassis must be OK.
8. Coolant temperature must be at least 80C. See «DIAGNOSTIC MODE 1: CHECK MEASURING VALUES»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq); PID 5, Coolant temperature.

Function test

1. Connect diagnostic tester. See «DIAGNOSTIC TESTER, CONNECTING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Start engine and let run at idle.
3. Under address word 33, select "Diagnostic mode 1: Checking measuring values."
4. Select the measuring value "PID 16: Air flow quantity at Mass Air Flow (MAF) sensor".
5. Check specified value of air flow quantity at Mass Air Flow (MAF) Sensor at idle

MAF SENSOR PID 16 DIAGNOSTIC - ENGINE CODE AHA

MAF SENSOR PID 16 DIAGNOSTIC - ENGINE CODE ATQ

1. End diagnosis and switch ignition off.

If specified value is obtained, but DTC memory has a DTC concerning Mass Air Flow (MAF) sensor

1. Check voltage supply of Mass Air Flow (MAF) sensor. See «VOLTAGE SUPPLY FOR MASS AIR FLOW (MAF) SENSOR, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .

If specified value is not obtained

1. Check signal and Ground (GND) wires of Mass Air Flow (MAF) sensor. See «CHECKING SIGNAL AND GROUND WIRES OF MASS AIR FLOW (MAF) SENSOR»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__checking-signal-and-ground-wires-of) .

Scheme 642

1. Disconnect 3-pin connector from Mass Air Flow (MAF) Sensor -G70-.
2. Connect multimeter to terminal 3 of connector and engine Ground (GND) for voltage measurement. see scheme 24: Identifying MAF Sensor Harness Connector Terminals (Engine Code AHA)
3. Switch ignition on. Specified value: at least 11.5 V
4. Switch ignition off.

If there is no voltage

1. Check wire between 3 -pin connector terminal 3 and relay carrier for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

Scheme 643

1. Disconnect 4-pin connector from Mass Air Flow (MAF) Sensor -G70-.
2. Connect multimeter to terminal 3 of connector and engine Ground (GND) for voltage measurement. see scheme 25: Identifying MAF Sensor Harness Connector Terminals (Engine Code ATQ)
3. Start engine, and let run at idle. Specified value: 11.0 to 15.0 V
4. Switch ignition off.

If there is no voltage

1. Check wire between 4 -pin connector terminal 3 and Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram. Wire resistance: max: 1.5ohm

1. Check signal and Ground (GND) wires of Mass Air Flow (MAF) sensor. See «CHECKING SIGNAL AND GROUND WIRES OF MASS AIR FLOW (MAF) SENSOR»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__checking-signal-and-ground-wires-of) .

Checking signal and Ground wires of Mass Air Flow (MAF) Sensor

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. Check wires between test box and 4 -pin connector for open circuits according to wiring diagram. Terminal 1+socket 13 Terminal 2+socket 12 Wire resistance: max: 1.5 ohm

Identifying MAF Sensor Harness Connector Terminals (Engine Code AHA). Scheme 644

1. Check wires between test box and 4 -pin connector for open circuits according to wiring diagram. Terminal 1+socket 53 Terminal 2+socket 27 Terminal 4 + socket 29 Wire resistance: max: 1.5 ohm

Identifying MAF Sensor Harness Connector Terminals (Engine Code ATQ). Scheme 645

1. Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+. Specified value: INFINITY ohm

If no DTCs are found in wires

1. Replace Mass Air Flow (MAF) Sensor -G70-. See «AIR FILTER, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__air-filter-disassembling-and-assembling) , item no. 7.
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Vehicles with engine code AHA (80 -pin Engine Control Module -ECM-)

Vehicles with engine code ATQ (121 -pin Engine Control Module -ECM-) VEHICLES WITH ENGINE CODE ATQ (121 -PIN ENGINE CONTROL MODULE -ECM-) .

Function

Components of Throttle Valve Control Module -J338- : Throttle drive (power accelerator actuation) -G186-, Angle sensor -1- for throttle drive (power accelerator actuation) - G187-, Throttle Position (TP) Sensor -G69- and Closed Throttle Position (CTP) Switch -F60-.

If the complete throttle valve control module is current-less (e.g. connector disconnected) the throttle valve moves into a particular, specified mechanical position, which signals an increased idle speed of 1200 RPM to 1300 RPM with an engine at operating temperature.

If only the Throttle drive (power accelerator actuation) - G186- is current -less, the throttle valve also moves into the specified mechanical position (emergency running gap), however, since Closed Throttle Position (CTP) Switch - F60- can still be recognized, an "almost normal" idle speed of approx. 900 RPM is reached via the respective ignition angle retardation.

If the Engine Control Module (ECM) detects a malfunction at Angle sensor -1- for throttle drive (power accelerator actuation) -G187-, Throttle drive (power accelerator actuation) -G186- is switched current-less by the Engine Control Module (ECM) and the throttle valve moves into the specified mechanical position (emergency running gap) again.

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

1. The respective fuses of Motronic Engine Control Module (ECM) - J220- must be OK: (Scheme 646): Identifying Fuse Holder
2. Battery voltage must be at least 11.5 volts.
3. All electrical consumers like, for example, lights and rear window heating must be switched off.
4. Parking brake must be engaged or else daylight driving lights will be switched on.
5. If vehicle is equipped with an A/C system, it must be switched off.
6. Ground (GND) connections between engine and chassis must be OK.
7. Throttle valve must not be damaged or dirty.
8. Throttle valve must be in Closed Throttle Position (CTP).
9. Adjustment of accelerator pedal cable must be OK, checking.
10. Coolant temperature must be at least 80°C. See «DIAGNOSTIC MODE 1: CHECK MEASURING VALUES»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq); PID 5, Coolant temperature.

Scheme 646

Scheme 647

1. Disconnect 8-pin connector -1- from throttle valve control module -2-. (Scheme 647): Disconnecting 8-Pin Connector From Throttle Valve Control Module
2. Connect multimeter to connector terminals 4+7 for voltage measurement. (Scheme 648): Identifying Throttle Valve Control Module Harness Connector Terminals
3. Switch ignition on. Specified value: 4.0 V... 6.0 V
4. Switch ignition off.
5. Connect multimeter to connector terminals 3+7 for voltage measurement.
6. Switch ignition on. Specified value: at least 9.0 V
7. Switch ignition off.
8. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 649): Identifying Throttle Valve Control Module Harness Connector Terminals
9. Check wires between test box and 8 -pin connector for open circuit according to wiring diagram: Terminal 1+socket 66 Terminal 2+socket 59 Terminal 3 + socket 69 Terminal 4 + socket 62 Terminal 5 + socket 75 Terminal 7 + socket 67 Terminal 8 + socket 74 Wire resistance: max: 1.5 ohm
10. Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+. Specified value: INFINITY ohm

If no malfunctions are found in wires

1. Check voltage supply of Engine Control Module (ECM). See «VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE (ECM), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Vehicles with engine code ATQ (121 -pin Engine Control Module -ECM-)

Note. Use only gold -plated terminals when servicing terminals in harness connector of throttle valve control module.

The throttle valve activation occurs via an electric motor (throttle drive) in the throttle valve control module. It is activated by the Engine Control Module (ECM) according to specifications of the two sensors, Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position -G185-. See FUNCTION OF E-GAS SYSTEM .

Components of Throttle Valve Control Module -J338

1. Throttle drive (power accelerator actuation) -G186
2. Angle sensor -1- for throttle drive (power accelerator actuation) -G187
3. Angle sensor -2- for throttle drive (power accelerator actuation) -G188

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 648

1. The respective fuses of Motronic Engine Control Module (ECM) - J220- must be OK: see scheme 32: Identifying Fuse Holder
2. Battery voltage must be at least 11.5 volts.
3. All electrical consumers like, for example, lights and rear window heating must be switched off.
4. Parking brake must be engaged or else daylight driving lights will be switched on.
5. If vehicle is equipped with an A/C system, it must be switched off.
6. Ground (GND) connections between engine and chassis must be OK.
7. Throttle valve must not be damaged or dirty.
8. Coolant temperature must be at least 80°C. See «DIAGNOSTIC MODE 1: CHECK MEASURING VALUES»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq); PID 5, Coolant temperature.

1. Connect diagnostic tester. See «DIAGNOSTIC TESTER, CONNECTING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Switch ignition on.
3. Under address word 33, select "Diagnostic mode 1: Checking measuring values."
4. Select the measuring value "PID 17: Throttle valve position (absolute)."
5. Check specified value of throttle valve position (absolute) at idle stop: PID 17: THROTTLE VALVE POSITION (ABSOLUTE) - AT IDLE STOP PID Diagnostic text Specified value: 17: Throttle valve position (absolute) Idle stop 12.0 to 16.0 %
6. Slowly depress accelerator pedal up to Wide Open Throttle (WOT) stop while observing the percentage display. The percentage display must increase uniformly.
7. Check specified value of throttle valve position (absolute) at Wide Open Throttle (WOT) stop: PID 17: THROTTLE VALVE POSITION (ABSOLUTE) - WIDE OPEN THROTTLE (WOT) STOP PID Diagnostic text Specified value: 17: Throttle valve position (absolute) Wide Open Throttle (WOT) stop 84.0...88.0 %
8. End diagnosis and switch ignition off.

If specified values are not obtained

Scheme 649

1. Disconnect 6-pin connector -2- at the throttle valve control module - 1-. (Scheme 651): Disconnecting 6-Pin Connector At Throttle Valve Control Module

Check resistance

1. Measure resistance of Throttle drive (power accelerator actuation) - G186- in Throttle Valve Control Module -J338- between terminals 3 + 5 Specified value: 3.0 to 200.0 ohms

Measuring Resistance Between Throttle Valve Control Module -J338- Terminals 3 And 5. Scheme 650

If specified value is not obtained

1. Replace Throttle Valve Control Module -J338-. See «THROTTLE VALVE CONTROL MODULE, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__throttle-valve-control-module-removing-and) .
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If specified value is obtained

1. Check voltage supply of throttle valve control module and wiring to control module. See «CHECKING VOLTAGE SUPPLY AND WIRING TO CONTROL MODULE»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .
2. Check Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position -G185-. See «THROTTLE POSITION (TP) SENSOR, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#fuel-supply-generic-scan-tool-28l-v6-aha-atq) .

If voltage supply and wires are OK

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

Scheme 651

1. Connect multimeter to connector terminals 2 + 6 for voltage measurement. (Scheme 652): Measuring Voltage Between Terminals 2 And 6 In Throttle Valve Control Module Harness Connector
2. Switch ignition on. Specified value: at least 4.5 V
3. Switch ignition off.
4. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 653): Identifying Throttle Valve Control Module Harness Connector Terminals
5. Check wires between test box and 6 -pin connector for open circuit according to wiring diagram: Terminal 1+socket 92 Terminal 2+socket 83 Terminal 3 + socket 117 Terminal 4 + socket 84 Terminal 5 + socket 118 Terminal 6 + socket 91 Wire resistance: max: 1.5 ohm
6. Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+. Specified value: INFINITY ohm

If no malfunctions are found in wires

1. Check voltage supply of Engine Control Module (ECM). See «VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE (ECM), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 652

1. The respective fuses of Motronic Engine Control Module (ECM) - J220- must be OK: (Scheme 654): Identifying Fuse Holder
2. Parking brake must be engaged or else daylight driving lights will be switched on.
3. Engine must be cold.

1. Connect diagnostic tester. See «DIAGNOSTIC TESTER, CONNECTING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Switch ignition on.
3. Under address word 33, select "Diagnostic mode 1: Checking measuring values."
4. Select the measuring value "PID 05: Coolant temperature".
5. Check specified value of coolant temperature: PID 05: COOLANT TEMPERATURE PID Diagnostic text Specified value: 05: Coolant temperature approx. coolant temperature

If specified value is not obtained

1. Continue test according to the following table: ENGINE COOLANT TEMPERATURE (ECT) SENSOR DIAGNOSTIC Indicated (1) ) Cause Continue testing approx. -40 °C Open circuit or short circuit to B+ See «CONTINUATION OF TEST IF INDICATION IS APPROX. -40 °C»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__continuation-of-test-if-indication-is) . approx. 143 °C Short circuit to Ground (GND) See «CONTINUATION OF TEST IF INDICATION IS APPROX. 143 ohmC»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__continuation-of-test-if-indication-is) . (1) If a temperature is indicated which differs greatly from ambient temperature of sensor, check sensor wires for contact resistance.

If specified value is obtained

1. Start engine and let run at idle. The temperature should climb uniformly.

Note. The temperature increases in increments of 1.0 °C. If the engine shows problems in certain temperature ranges and if the temperature does not climb uniformly, the temperature signal is intermittent and the sensor should be replaced.

Continuation of test if indication is approx. -40 °C

1. Disconnect 4-pin connector from Engine Coolant Temperature (ECT) Sensor -G62- with Engine Coolant Temperature (ECT) Sensor -G2- (arrow)

Scheme 653

1. Bridge terminals 1 + 3 of connector using the respective adapter cables and observe the indication on display. see scheme 38: Bridging ECT Sensor Harness Connector Terminals 1 And 3 - Engine Code AHA

Scheme 654

1. Bridge terminals 3 + 4 of connector using the respective adapter cables and observe the indication on display. (Scheme 656): Bridging ECT Sensor Harness Connector Terminals 3 And 4 - Engine Code ATQ

If indication jumps to approx. 143 °C

1. End diagnosis and switch ignition off.
2. Replace Engine Coolant Temperature (ECT) Sensor -G62- with Engine Coolant Temperature (ECT) Sensor -G2-, item 33 .
3. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
4. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If indication remains at approx. -40 °C

1. End diagnosis and switch ignition off.
2. Check wires according to wiring diagram. See «CONTINUATION OF TEST IF INDICATION IS APPROX. 143 ohmC»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__continuation-of-test-if-indication-is) .

Continuation of test if indication is approx. 143 ohmC

1. Disconnect 4 -pin connector from Engine Coolant Temperature (ECT) Sensor -G62- with Engine Coolant Temperature (ECT) Sensor -G2- (arrow)

If indication jumps to approx. -40 ohmC

1. End diagnosis and switch ignition off.
2. Replace Engine Coolant Temperature (ECT) Sensor - G62- with Engine Coolant Temperature (ECT) Sensor - G2-, item 33 .
3. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
4. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If indication remains at approx. 143 ohmC

1. End diagnosis and switch ignition off.
2. Check wires according to wiring diagram. See «CONTINUATION OF TEST IF INDICATION IS APPROX. 143 ohmC»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__continuation-of-test-if-indication-is) .

Checking wiring

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. Check wires between test box and 4 -pin connector for open circuits according to wiring diagram. Terminal 1+socket 53 Terminal 3 + socket 67 Wire resistance: max: 1.5

1. Check wires between test box and 4 -pin connector for open circuits according to wiring diagram. Terminal 3 + socket 108 Terminal 4 + socket 93 Wire resistance: max: 1.5 ohm

Identifying ECT Sensor Harness Connector Terminals 3 And 4 - Engine Code ATQ. Scheme 655

1. Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+. Specified value: INFINITY ohm

If no malfunctions are found in wires

Scheme 656

1. Perform a resistance measurement at Engine Coolant Temperature (ECT) Sensor -G62- terminal 1 (signal) and 3 (Ground -GND-). (Scheme 659): Identifying ECT Sensor Connector Terminals 1 (Signal) And 3 (Ground) - Engine Code AHA

1. Measure resistance at Engine Coolant Temperature (ECT) Sensor - G62-, terminals C (signal) and D (Ground -GND-).

Identifying ECT Sensor Connector Terminals C (Signal) And D (Ground) - Engine Code ATQ. Scheme 657

Range A displays resistance values for the temperature range of 0 to 50 °C, range B displays resistance values for the temperature range of 50 to 100 °C.

ECT Sensor Temperrature Versus Resistance Range Graph. Scheme 658

Read-out examples

1. 30 °C is in range A and corresponds to a resistance of 1.5 to 2.0 kohm
2. 80 °C is in range B and corresponds to a resistance of 275 to 375ohm

If specified value is not obtained

1. Replace Engine Coolant Temperature (ECT) Sensor -G62- with Engine Coolant Temperature (ECT) Sensor -G2-, item 33 .
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If no malfunctions are detected in the wires and the resistance values are OK

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram
4. Chilling spray (commercially available)

Scheme 659

1. The respective fuses of Motronic Engine Control Module (ECM) - J220- must be OK: (Scheme 661): Identifying Fuse Holder
2. Parking brake must be engaged or else daylight driving lights will be switched on.

1. Connect diagnostic tester. See «DIAGNOSTIC TESTER, CONNECTING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Switch ignition on.
3. Under address word 33, select "Diagnostic mode 1: Checking measuring values."
4. Select the measuring value "PID 15: Intake air temperature".
5. Check specified value of intake air temperature: PID 15: INTAKE AIR TEMPERATURE PID Diagnostic text Specified value: 15: Intake Air Temperature (IAT) approx. ambient temperature

If specified value is not obtained

1. Continue test according to the following table: INTAKE AIR TEMPERATURE SENSOR DIAGNOSTIC Indicated (1) ) Cause Continue testing approx. -40 °C Open circuit or short circuit to B+ See «CONTINUATION OF TEST IF INDICATION IS APPROX. -40 °C»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) . approx. 143 °C Short circuit to Ground (GND) See «CONTINUATION OF TEST IF INDICATION IS APPROX. 143 °C»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) . (1) If a temperature is indicated which is below the ambient temperature of sensor, first check sensor wires for contact resistance. Note that while the vehicle is standing still the sensor might warm up due to radiant heat.

If specified value is obtained

Removing Intake Air Temperature Sensor -G42. Scheme 660

1. Remove Intake Air Temperature (IAT) Sensor -G42-. Plug connector back in.
2. Remember the intake air temperature value.
3. Spray the sensor with commercially available chilling spray while observing the temperature value. The temperature should decrease.
4. End diagnosis and switch ignition off.

If the intake air temperature does not drop

1. Replace Intake Air Temperature (IAT) Sensor -G42-, item 10 .
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Scheme 661

1. Disconnect connector -1- from Intake Air Temperature (IAT) Sensor - G42- (-2-). see scheme 47: Disconnecting Connector From Intake Air Temperature Sensor - G42
2. Bridge terminals 1 + 2 of connector using the respective adapter cables while observing the indication on display. see scheme 48: Identifying Intake Air Temperature Sensor Harness Connector Terminals

If indication jumps to approx. 143 °C

1. End diagnosis and switch ignition off.
2. Replace Intake Air Temperature (IAT) Sensor -G42-, item 10 .
3. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
4. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If indication remains at approx. -40 °C

1. End diagnosis and switch ignition off.
2. Check wires according to wiring diagram. See «CHECKING WIRING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .

1. Disconnect connector -1- from Intake Air Temperature (IAT) Sensor - G42- (-2-). (Scheme 664): Disconnecting Connector From Intake Air Temperature (IAT) Sensor - G42

If indication jumps to approx. -40 °C

1. End diagnosis and switch ignition off.
2. Replace Intake Air Temperature (IAT) Sensor -G42-, item 10 .
3. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
4. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If indication remains at approx. 143 °C

1. End diagnosis and switch ignition off.
2. Check wires according to wiring diagram. See «CHECKING WIRING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. Check wires between test box and 2 -pin connector for open circuit according to wiring diagram. Terminal 1+socket 54 Terminal 2+socket 67 Wire resistance: max: 1.5 ohm

Identifying Intake Air Temperature Sensor Harness Connector Terminals. Scheme 662

1. Check wires between test box and 2 -pin connector for open circuit according to wiring diagram. Terminal 1+socket 85 Terminal 2+socket 108 Wire resistance: max: 1.5 ohm

Identifying Intake Air Temperature Sensor Harness Connector Terminals. Scheme 663

1. Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+. Specified value: INFINITY ohm

If no malfunctions are found in wire

Scheme 664

1. Measure resistance at Intake Air Temperature (IAT) Sensor -G42-. (Scheme 666): Measuring Resistance At Intake Air Temperature (IAT) Sensor -G42

Range A displays resistance values for the temperature range of 0..0.50 °C, range B displays resistance values for the temperature range of 50..0.100 °C.

IAT Sensor Temperature Versus Resistance Range Graph. Scheme 665

Read-out examples

1. 30 °C is in range A and corresponds to a resistance of 1.5 to 2.0 kohm
2. 80 °C is in range B and corresponds to a resistance of 275 to 375ohm

If specified value is not obtained

1. Replace Intake Air Temperature (IAT) Sensor -G42-, item 10 .
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If no malfunctions are detected in the wires and the resistance values are OK

1. Replace Motronic Engine Control Module (ECM) -J220-, see «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

The Engine Speed (RPM) Sensor -G28- detects engine speed and reference marks. Without an engine speed signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop immediately.

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

1. Disconnect gray 3-pin harness connector (arrow) to the engine speed (RPM) sensor. see scheme 54: Locating Gray 3-Pin Harness Connector (Arrow) To The Engine Speed (RPM) Sensor

Note. To reach this harness connector, remove coolant reservoir attachment screws and tilt coolant reservoir to the side. The coolant hoses remain connected.

Scheme 666

1. Measure sensor resistance between terminals 1 + 2 at connector to sensor. Specified value: 480 to 1000 ohm see scheme 55: Measuring Resistance Between Terminals 1 And 2 Of Engine Speed (RPM) Sensor Connector - Engine Code AHA

1. Measure sensor resistance between terminals 2 + 3 at connector to sensor. Specified value: 730 to 1000 ohm (Scheme 669): Measuring Resistance Between Terminals 2 And 3 Of Engine Speed (RPM) Sensor Connector - Engine Code ATQ

1. Check sensor for short circuit between terminals 1 + 2 as well as 1 + 3. Specified value: INFINITY ohm

If specified values are not obtained

1. Replace Engine Speed (RPM) Sensor -G28-.
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If no DTC is found on sensor

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. Check wires between test box and 3 -pin connector for open circuits according to wiring diagram. Terminal 1+socket 67 Terminal 2+socket 63 Terminal 3 + socket 56 Wire resistance: max: 1.5 ohm

Identifying Engine Speed (RPM) Sensor Harness Connector Terminals - Engine Code AHA. Scheme 667

1. Check wires between test box and 3 -pin connector for open circuits according to wiring diagram. Terminal 1+socket 108 Terminal 2+socket 90 Terminal 3 + socket 82 Wire resistance: max: 1.5 ohm

Identifying Engine Speed (RPM) Sensor Harness Connector Terminals - Engine Code ATQ. Scheme 668

1. Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+. Specified value: INFINITY ohm

If no malfunctions are found in wires

1. Remove sensor and check sensor wheel for secure fit, damage, and run-out.

Note. There is a larger-sized gap on the sensor wheel. This gap is the reference mark and does not mean that the sensor wheel is damaged.

If nothing seems to be wrong with the sensor wheel

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1527 voltage test lamp
3. VAG1594 connector test kit
4. Wiring diagram

Scheme 669

1. The respective fuses of Cylinder 1 Fuel Injector -N30- to Cylinder 4 Fuel Injector -N33-, Cylinder 5 Fuel Injector -N83-, Cylinder 6 Fuel Injector -N84- must be OK: (Scheme 670): Identifying Fuse Holder
2. Fuel Pump (FP) Relay -J17- must be OK, check
3. Battery voltage must be at least 11.5 volts.
4. All electrical consumers like, for example, lights and rear window heating must be switched off.
5. Parking brake must be engaged or else daylight driving lights will be switched on.
6. For vehicles with automatic transmission, selector lever must be in position -P- or -N-.
7. If vehicle is equipped with an A/C system, it must be switched off.
8. Ground (GND) connections between engine and chassis must be OK.
9. Engine speed (RPM) sensor must be OK. See «ENGINE SPEED (RPM) SENSOR -G28-, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq).
10. Ignition switched off.

1. Pull connectors -1- off connection -2- of all fuel injectors. (Scheme 671): Pulling Connectors -1- Off Of Fuel Injectors

1. Test resistance of fuel injectors between terminals. Specified value: 13.5 to 15.5 ohm (Scheme 672): Measuring Resistance Values Of Fuel Injectors

If specified value is not obtained

1. Replace malfunctioning fuel injector, item 7 . See «FUEL RAIL WITH FUEL INJECTORS, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-rail-with-fuel-injectors-disassembling) .

Note the following when installing the fuel injectors

1. Replace O -rings on all fuel injectors and wet them slightly with clean motor oil.
2. Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
3. Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to press it in.

1. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Scheme 670

1. Connect diode test lamp to connector of fuel injector to be tested terminal 1 and Ground (GND). (Scheme 673): Identifying Fuel Injector Harness Connector Terminals
2. Operate starter and test voltage supply for fuel injector. LED must light up.
3. Switch ignition off.

If LED does not light up

1. Check wire between 2 -pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

Scheme 671

1. Connect diode test lamp to the connector terminals of the fuel injector to be checked. (Scheme 674): Identifying Fuel Injector Harness Connector Terminals
2. Operate starter and test activation of fuel injector. LED should flicker.
3. Switch ignition off.

If LED does not flicker

Scheme 672

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 675): Identifying Fuel Injector Harness Connector Terminals
2. Check wires between test box and 2 -pin connector for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

FUEL INJECTOR RESISTANCE DATA - ENGINE CODE AHA

FUEL INJECTOR RESISTANCE DATA - ENGINE CODE ATQ

1. Also check wires for short circuit to B+ and Ground (GND). Specified value: INFINITY ohm

If there is no malfunction in wire connection

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

1. VAG1348/3A remote control with VAG1348/3-2 adapter cable
2. V.A.G 1602 tester for quantity of injected fuel

Without illustration

Scheme 673

1. VAG1594A connector test kit (Scheme 676): Identifying Special Tool

Test requirement

1. Fuel pressure must be OK. See «FUEL PRESSURE REGULATOR AND RETAINING PRESSURE, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-pressure-regulator-and-residual-pressure) .

Scheme 674

Scheme 675

Scheme 676

1. First, remove intake hose between Mass Air Flow (MAF) sensor and intake air scoop.
2. Pull connectors -1- off connection -2- of all fuel injectors. (Scheme 677): Pulling Connectors Off Of All Fuel Injectors
3. Unscrew fuel rail from intake manifold (arrows). (Scheme 678): Unscrewing Fuel Rail From Intake Manifold
4. Disconnect vacuum hose from fuel pressure regulator. (Scheme 679): Disconnecting Vacuum Hose From Fuel Pressure Regulator
5. Lift fuel rail with fuel injectors off intake manifold and support it.
6. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq).

Checking Proper Seal

1. Switch ignition on.

1. Bridge sockets 1 + 4 of test box with the respective adapter cables. Fuel Pump (FP) must run.

1. Bridge sockets 62 + 65 of test box with the respective adapter cables. Fuel Pump (FP) must run.

1. Check proper seal of fuel injectors (visual inspection). With Fuel Pump (FP) running, only 1 to 2 drops per minute should escape from each valve.
2. Disconnect connection between test box sockets.
3. Switch ignition off.

If fuel loss is greater

1. Replace malfunctioning fuel injector, item 7 .

Note the following when installing the fuel injectors

1. Replace O -rings on all fuel injectors and wet them slightly with clean motor oil.
2. Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
3. Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to press it in.

1. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Scheme 677

Scheme 678

1. Insert a fuel injector to be tested into a measuring tube of VAG1602 tester for fuel injection quantity. (Scheme 680): Inserting Fuel Injector To Be Tested Into Measuring Tube Of VAG1602 Tester
2. Using respective adapter cables, connect one terminal of fuel injector to be checked to engine Ground (GND).
3. Use adapter cable to connect second terminal of fuel injector to VAG1348/3 remote control with VAG1348/3-2 adapter cable. (Scheme 681): Connecting Fuel Injector To VAG1348/3 Remote Control With VAG1348/3-2 Adapter Cable
4. Connect alligator clip to B+.
5. Switch ignition on.

1. Bridge sockets 1 + 4 of test box with the respective adapter cables. Fuel Pump (FP) must run.

1. Bridge sockets 62 + 65 of test box with the respective adapter cables. Fuel Pump (FP) must run.

1. Operate VAG1348/3 remote control for 30 seconds.
2. Repeat test on other fuel injectors. Use new graduated measuring glasses for this.

Note. Also check spray pattern when checking injection quantity. Spray pattern must be the same for all injectors

1. After all fuel injectors have been activated, place graduated measuring glasses on a level surface and compare quantity of injected fuel. Specified value: 90 to 125 ml per injector
2. Disconnect connection between test box sockets.
3. Switch ignition off.

If the measured value of one or more fuel injectors is below or above the indicated specified value

1. Replace malfunctioning fuel injector, item 7 . See «FUEL RAIL WITH FUEL INJECTORS, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-rail-with-fuel-injectors-disassembling)

Installation of fuel injectors is the same in reverse order.

Note the following

1. Replace O -rings on all fuel injectors and wet them slightly with clean motor oil.
2. Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
3. Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to press it in.

1. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Fuel pressure regulator and residual pressure, checking

Function

The fuel pressure regulator controls the fuel pressure as a function of the Manifold Absolute Pressure (MAP).

The specified value for this test is dependent on the working pressure of the Fuel Pump (FP). This is

about 4.0 bar positive pressure

Scheme 679

1. V.A.G 1318 pressure gauge
2. VAG1318/7 adapter
3. VAG1318/10 adapter
4. VAG1318/13 adapter (Scheme 682): Identifying Special Tools

1. Delivery quantity of Fuel Pump (FP) OK. See «FUEL PUMP, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#fuel-supply-generic-scan-tool-28l-v6-aha-atq) .

Test sequence

Scheme 680

Scheme 681

1. Unscrew fuel supply hose -1- from fuel rail -2-.
2. Connect VAG1318 pressure gauge using adapters VAG1318/7, /10 and /13. (Scheme 683): Connecting VAG1318 Pressure Gauge To Fuel System Using Adapters VAG1318/7, /10 and /13
3. Open shut-off valve of pressure gauge. The lever points in the direction of flow (arrow).
4. Start engine and let run at idle.
5. Measure fuel pressure. Specified value: about 3.5 bar positive pressure (Scheme 684): Disconnecting Vacuum Hose From Fuel Pressure Regulator
6. Disconnect vacuum hose from fuel pressure regulator (arrow). Fuel pressure should rise to about 4.0 bar positive pressure.

Note. If fuel should escape at the vacuum connection of the pressure regulator, replace pressure regulator.

1. Switch ignition off.
2. Check for proper seal and residual pressure by observing pressure drop on pressure gauge. After 10 minutes at least 2.2 bar positive pressure should still be present.

If residual pressure falls below 2 bar positive pressure

Scheme 682

1. Start engine and let run at idle.
2. Wait until pressure has risen, and then switch off ignition. Simultaneously close shut-off valve of VAG1318 pressure gauge (lever perpendicular to direction of flow -arrow-). (Scheme 685): Identifying Close Shut-Off Valve Of VAG1318 Pressure Gauge
3. Observe pressure drop on pressure gauge.

If pressure does not drop

1. Test check-valve of Fuel Pump (FP). See «FUEL PUMP, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#fuel-supply-generic-scan-tool-28l-v6-aha-atq) .

If pressure does drop again

Scheme 683

1. Open stop valve of pressure gauge V.A.G 1318 (lever in direction of flow -arrow-). (Scheme 686): Identifying Open Stop Valve Of Pressure Gauge V.A.G 1318
2. Start engine and let run at idle.
3. Wait until pressure has risen, and then switch off ignition. Simultaneously pinch return hose -3- tightly together.

If pressure does not drop

1. Replace fuel pressure regulator. See «FUEL RAIL WITH FUEL INJECTORS, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-rail-with-fuel-injectors-disassembling) , item 5.

If pressure does drop again

1. Check whether line connections, O-rings in fuel rail, and fuel injectors are properly sealed.
2. Check whether pressure gauge is properly sealed.

Note. Before removing pressure gauge, put cleaning rags back around line connection which is to be disconnected.

1. Engine leak detection spray G 001 800 A1

1. Coolant temperature must be at least 80°C. See «DIAGNOSTIC MODE 1: CHECK MEASURING VALUES»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) ; PID 5, Coolant temperature.

Note. The negative pressure in the intake system sucks in the leak detection spray with the unmetered air. Leak detection spray decreases ignition quality and performance of the fuel mixture. This causes a drop in engine speed and changes the value produced by the Heated Oxygen Sensor (HO2S). It is absolutely necessary to follow the safety precautions listed on the can.

1. Connect diagnostic tester. See «DIAGNOSTIC TESTER, CONNECTING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Start engine and let run at idle.
3. Under address word 33, select "Diagnostic mode 1: Checking measuring values."
4. Select the following measuring values and check the specified values at idle

DIAGNOSTIC MODE 1: CHECKING MEASURING VALUES (PID) - ENGINE CODE AHA

DIAGNOSTIC MODE 1: CHECKING MEASURING VALUES (PID) - ENGINE CODE ATQ

Note. Bank 1 = Cylinder bank 1, in direction of travel, right Bank 2 = Cylinder bank 2, in direction of travel, left

1. Spray intake system parts with engine leak detection spray in a systematic manner.

If engine speed drops or if the short -term gasoline-air ratio changes

1. End diagnosis and switch ignition off.
2. Check sprayed part of intake system for leaks, and eliminate the error.
3. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
4. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Oxygen Sensor (O2S) and oxygen sensor control before Three Way Catalytic Converter (TWC), checking

Note. When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 684

1. The respective fuses of Heated Oxygen Sensor (HO2S) -G39- and Heated Oxygen Sensor (HO2S) 2 -G108- must be OK: (Scheme 687): Identifying Fuse Holder
2. Battery voltage must be at least 11.5 volts.
3. All electrical consumers like, for example, lights and rear window heating must be switched off.
4. Parking brake must be engaged or else daylight driving lights will be switched on.
5. If vehicle is equipped with an A/C system, it must be switched off.
6. Ground (GND) connections between engine and chassis must be OK.
7. Exhaust system must be properly sealed between catalytic converter and cylinder head.
8. Coolant temperature must be at least 80°C. See «DIAGNOSTIC MODE 1: CHECK MEASURING VALUES»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq); PID 5, Coolant temperature.
9. Oxygen sensor heaters for oxygen sensors before catalytic converter must be OK. See «COMPONENTS, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq).

Scheme 685

1. Select the following output of oxygen sensor signals and check whether the specified values are being reached. See «DIAGNOSTIC MODE 5: CHECK OUTPUT OF OXYGEN SENSOR SIGNALS»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 688): Identifying Output Of Oxygen Sensor Signals At Idle
2. Check the specified values of the output of oxygen sensor signals at idle

*) V = Voltage in Volts (oxygen sensor signal)

**) t = Time in seconds

OUTPUT OF OXYGEN SENSOR (BEFORE TWC) SIGNALS (PID) - ENGINE CODE AHA

OUTPUT OF OXYGEN SENSOR (BEFORE TWC) SIGNALS (PID) - ENGINE CODE ATQ

Note. Cylinder bank 1 = in driving direction, right Cylinder bank 2 = in driving direction, left

If specified values are obtained

1. End diagnosis and switch ignition off.

If specified values are not obtained

1. End diagnosis and let engine continue to run at idle.
2. Check primary voltage. See «CHECKING PRIMARY VOLTAGE»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .

Scheme 686

Scheme 687

1. Disconnect 4-pin harness connector to the respective oxygen sensor: Heated Oxygen Sensor (HO2S) -G39-, bank 1, 4 -pin harness connector (black, arrow). (Scheme 689): Identifying Heated Oxygen Sensor (Ho2S) -G39-, Bank 1, 4 -Pin Harness Connector (Black) Heated Oxygen Sensor (HO2S) 2 -G108-, bank 2, 4 -pin harness connector (black, arrow). (Scheme 690): Identifying Heated Oxygen Sensor (Ho2S) 2 -G108-, Bank 2, 4 -Pin Harness Connector (Black)

Note. To reach this harness connector, remove coolant reservoir attachment screws and tilt coolant reservoir to the side. The coolant hoses remain connected.

Scheme 688

1. Connect multimeter for voltage measurement to terminals 3 + 4 of the respective connector to Engine Control Module (ECM) and measure primary voltage. (Scheme 691): Identifying HO2S Harness Connector Terminals Specified value: 0.40 to 0.50 volts
2. Switch ignition off.

If specified value is not obtained on one or both Heated Oxygen Sensors (HO2S)

1. Test oxygen sensor wires. See «CHECKING OXYGEN SENSOR WIRES»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq)

If specified values are obtained

1. Replace the respective oxygen sensor: Heated Oxygen Sensor (HO2S) -G39-, bank 1. See «EXHAUST MANIFOLD, FRONT EXHAUST PIPE WITH THREE WAY CATALYTIC CONVERTER (TWC) AND ATTACHMENTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__exhaust-manifold-front-exhaust-pipe-with) , item 1. Heated Oxygen Sensor (HO2S) 2 -G108-, bank 2. See «MUFFLERS WITH MOUNTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) , item 15.
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Scheme 689

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 692): Identifying HO2S Harness Connector Terminals
2. Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

CHECKING HO2S (BEFORE TWC) WIRES - ENGINE CODE AHA

CHECKING HO2S (BEFORE TWC) WIRES - ENGINE CODE ATQ

1. Also check wires for short circuit to B+ and Ground (GND). Specified value: INFINITY ohm

If no malfunctions are found in wires

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

Oxygen Sensor and oxygen sensor control behind Three Way Catalytic Converter (TWC), checking

Note. When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 690

1. The respective fuses of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- must be OK: (Scheme 693): Identifying Fuse Holder
2. Battery voltage must be at least 11.5 volts.
3. All electrical consumers like, for example, lights and rear window heating must be switched off.
4. Parking brake must be engaged or else daylight driving lights will be switched on.
5. If vehicle is equipped with an A/C system, it must be switched off.
6. Ground (GND) connections between engine and chassis must be OK.
7. Exhaust system must be properly sealed between catalytic converter and cylinder head.
8. Coolant temperature must be at least 80°C. See «DIAGNOSTIC MODE 1: CHECK MEASURING VALUES»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq); PID 5, Coolant temperature.
9. Oxygen sensor heater for oxygen sensors behind catalytic converter must be OK, check «OXYGEN SENSOR HEATER FOR OXYGEN SENSORS BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-heater-for-oxygen-sensors).

Scheme 691

1. Select the following output of oxygen sensor signals and check whether the specified values are being reached. See «DIAGNOSTIC MODE 5: CHECK OUTPUT OF OXYGEN SENSOR SIGNALS»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 694): Identifying Output Of Oxygen Sensor Signals At Idle
2. Check the specified values of the output of oxygen sensor signals at idle

*) V = Voltage in Volts (oxygen sensor signal)

**) t = Time in seconds

OUTPUT OF OXYGEN SENSOR (BEHIND TWC) SIGNALS (PID) - ENGINE CODE AHA

OUTPUT OF OXYGEN SENSOR (BEHIND TWC) SIGNALS (PID) - ENGINE CODE ATQ

Note. Cylinder bank 1 = in driving direction, right Cylinder bank 2 = in driving direction, left

If specified values are obtained

1. End diagnosis and switch ignition off.

If specified values are not obtained

1. End diagnosis and let engine continue to run at idle.
2. Check primary voltage. See «CHECKING PRIMARY VOLTAGE»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .

Scheme 692

Scheme 693

Scheme 694

1. Disconnect 4-pin harness connector to the respective oxygen sensor: Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, bank 1, 4 -pin harness connector (green) (arrow). (Scheme 695): Identifying Oxygen Sensor (O2S) Behind Three Way Catalytic Converter -G130-, Bank 1, 4 -Pin Harness Connector (Green) Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, bank 2, 4 -pin harness connector (brown, arrow). (Scheme 696): Identifying Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter -G131-, Bank 2, 4 -Pin Harness Connector (Brown)
2. Connect multimeter for voltage measurement to terminals 3 + 4 of the respective connector to Engine Control Module (ECM) and measure primary voltage. (Scheme 697): Identifying HO2S Harness Connector Terminals Specified value: 0.40 to 0.50 volts
3. Switch ignition off.

If specified value is not obtained on one or both Heated Oxygen Sensors (HO2S)

1. Test oxygen sensor wires. See «CHECKING OXYGEN SENSOR WIRES»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) .

If specified values are obtained

1. Replace the respective oxygen sensor: Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, bank 1. See «MUFFLERS WITH MOUNTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) , item 4. Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, bank 2. See «MUFFLERS WITH MOUNTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) , item 11
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Scheme 695

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). (Scheme 698): Identifying HO2S Harness Connector Terminals
2. Check wires between test box and 4 -pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

CHECKING HO2S (BEHIND TWC) WIRES - ENGINE CODE AHA

CHECKING HO2S (BEHIND TWC) WIRES - ENGINE CODE ATQ

1. Also check wires for short circuit to B+ and Ground (GND). Specified value: INFINITY ohm

If no malfunctions are found in wires

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

The Engine Control Module (ECM) controls fuel injection, the throttle valve control module, oxygen sensor control, ignition, knock control, EVAP canister purge regulator valve, engine speed limitation via fuel injectors and fuel pump relay, camshaft adjustment and On Board Diagnostic (OBD).

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 696

1. The respective fuses of Motronic Engine Control Module (ECM) - J220- must be OK: (Scheme 699): Identifying Fuse Holder Electrical Wiring Diagrams, Troubleshooting & Component Locations
2. Fuel Pump (FP) Relay -J17- must be OK, check
3. Generator (GEN) must be OK, checking
4. Battery voltage must be at least 11.5 volts.
5. All electrical consumers like, for example, lights and rear window heating must be switched off.
6. Parking brake must be engaged or else daylight driving lights will be switched on.
7. If vehicle is equipped with an A/C system, it must be switched off.
8. Ground (GND) connections between engine and chassis must be OK.

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Checking voltage supply at terminal 30; Vehicles with engine code AHA

1. Measure voltage supply between sockets 2 + 3 of test box. Specified value: at least 11.5 V

1. Measure voltage supply between sockets 1 + 62 and 2 + 62 of test box. Specified value: at least 11.5 V

If specified value is not obtained

1. Check wire connections to relay carrier and Ground (GND) connection of Engine Control Module (ECM) according to wiring diagram
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Checking voltage supply at terminal 15

Vehicles with engine code AHA

1. Measure voltage supply between sockets 1 + 2 of test box.

1. Measure voltage supply between sockets 1 + 3 and 2 + 3 of test box.

1. Switch ignition on. Specified value: at least 11.5 V

If specified value is not obtained

1. Check wire connections to relay carrier and Ground (GND) connection of Engine Control Module (ECM) according to wiring diagram
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Engine Control Module (ECM), replacing

Note. To achieve optimal anti -theft protection for the vehicle, an anti-theft immobilizer was installed. The anti -theft immobilizer is a system for enabling/locking the Engine Control Module (ECM) via the W -wire. So that this system cannot be circumvented, it is necessary to perform adaptation of the anti -theft immobilizer using the VAS 5052 in the On Board Diagnostic (OBD) function. The great availability of equipment options makes adaptation of the Engine Control Module (ECM) necessary (e.g. cruise control system). This "writing" function is not possible with the generic scan tool, therefore it is necessary to use the VAS 5052 in On Board Diagnostic (OBD) function for this purpose. Procedure to replace Engine Control Module (ECM): See ENGINE CONTROL MODULE (ECM) (WITHOUT METAL ANTI-THEFT HOUSING), REPLACING or ENGINE CONTROL MODULE (ECM) (WITH METAL ANTI-THEFT HOUSING), REPLACING .

1. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 697

1. The respective fuses of Motronic Engine Control Module (ECM) - J220- must be OK: (Scheme 700): Identifying Fuse Holder
2. Battery voltage must be at least 11.5 volts.
3. Speedometer -G21- must be OK.

Note. To test speed signal, vehicle must be driven. Doing this requires a second person.

1. Connect diagnostic tester. See «DIAGNOSTIC TESTER, CONNECTING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Start engine and let run at idle.
3. Under address word 33, select "Diagnostic mode 1: Checking measuring values."
4. Select the measuring value "PID 13: Vehicle speed".
5. Perform a road test, and have the 2nd person observe the indication on the display.
6. Check specified value of the vehicle speed: PID 13: VEHICLE SPEED PID Diagnostic text Specified value: 13: Vehicle speed approx. vehicle speed
7. End diagnosis and switch ignition off.

If no speed is indicated

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. Connect multimeter between sockets 3 + 20 (speed signal) of test box for voltage measurement.

1. To measure voltage, connect multimeter between sockets 3 (terminal 15) +54 (speed signal) of test box.

1. Jack up front left wheel.
2. Switch ignition on.
3. Rotate front wheel, and observe voltage indicated while doing so. Specified value: 0.0 to at least 4.0 V, fluctuating

Note. The right front wheel must not turn during this, hold it steady if necessary.

If indicated voltage does not oscillate

1. Remove instrument cluster: Repair Manual, Electrical Equipment, Repair Group 90, Instrument cluster, removing and installing
2. Check wire connection from Engine Control Module (ECM) to Speedometer -G21- according to wiring diagram.
3. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
4. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

Scheme 698

1. The respective fuses of Clutch Vacuum Vent Valve Switch -F36- must be OK: (Scheme 701): Identifying Fuse Holder
2. Battery voltage must be at least 11.5 volts.
3. All electrical consumers like, for example, lights and rear window heating must be switched off.
4. Parking brake must be engaged or else daylight driving lights will be switched on.
5. If vehicle is equipped with an A/C system, it must be switched off.
6. Ground (GND) connections between engine and chassis must be OK.
7. Ignition switched off.

Scheme 699

1. Remove driver-side storage compartment.
2. Disconnect 2-pin connector from Clutch Vacuum Vent Valve Switch -F36-.
3. Measure resistance between terminals 1 + 2 of switch. see scheme 91: Measuring Resistance Between Clutch Vacuum Vent Valve Switch Terminals 1 + 2 Of Switch Specified value Clutch pedal not depressed: max. 1.5 ohm Clutch pedal depressed: INFINITY ohm

If specified values are not obtained

1. Replace Clutch Vacuum Vent Valve Switch -F36-.
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If specified values are obtained

Scheme 700

1. Connect multimeter between terminal 1 and Ground (GND) for voltage measurement. see scheme 92: Measuring Voltage Between Clutch Vacuum Vent Valve Switch Harness Connector Terminal 1 And Ground Specified value: at least 11.5 V

If specified value is not obtained

1. Check wire between 2 -pin connector terminal 1 and central electronics for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

If specified value is obtained

Scheme 701

1. Connect test box to control module wiring harness. See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq). see scheme 93: Identifying Clutch Vacuum Vent Valve Switch Harness Connector Terminals
2. Check wire between test box and 2 -pin connector for open circuit according to wiring diagram. Terminal 2+socket 39 Wire resistance: max: 1.5 ohm
3. Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+. Specified value: INFINITY ohm

If no malfunctions are detected in the wires and the resistance values are OK

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

The Engine Control Module (ECM) communicates with all databus-capable control modules via a CAN databus.

These databus -capable control modules are connected via two data bus wires which are twisted together (CAN_High and CAN_Low), and exchange information (messages). Missing information on the databus is recognized as a malfunction and stored.

Trouble-free operation of the CAN -Bus requires that it have a terminal resistance. This central terminal resistor is located in the Engine Control Module (ECM).

1. VAG1526 multimeter or VAG1715 multimeter
2. VAG1594 connector test kit
3. Wiring diagram

1. DTC "P0600 Serial Communication Link" was detected by the Engine Control Module (ECM). See «DIAGNOSTIC MODE 3: CHECK DTC MEMORY»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Ignition switched off.

1. Connect test box to Engine Control Module (ECM). See «TEST BOX, CONNECTING FOR WIRING TEST»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) . During this, wiring harness to Engine Control Module (ECM) is NOT connected.
2. Check the central termination resistor in the Engine Control Module (ECM)
3. To do this, measure resistance between test box socket 58 + 60: Specified value: 60...72 ohm

If resistance value is not in expected range

1. Replace Motronic Engine Control Module (ECM) -J220-. See «ENGINE CONTROL MODULE (ECM), REPLACING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__engine-control-module-ecm-replacing) .

If resistance value is in expected range

1. Disconnect test box from Engine Control Module (ECM).
2. Connect test box to control module wiring harness.
3. Check CAN data bus wires for shorts among one another
4. To do this, perform a resistance measurement between test box sockets 58 + 60: Specified value: INFINITY ohm

If specified value is obtained (wires have no shorts)

1. Eliminate error in wires (see circuit diagram).

See also:
• MALFUNCTION INDICATOR LAMP (MIL) IN INSTRUMENT CLUSTER, CHECKING
• ELECTRONIC POWER CONTROL (EPC) WARNING LAMP IN INSTRUMENT CLUSTER, CHECKING
• SECONDARY AIR SYSTEM, CHECKING FOR PROPER SEAL
• SECONDARY AIR INJECTION (AIR) VALVE, CHECKING
• IGNITION, SERVICING
• EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR VALVE, CHECKING
• CONNECTING PIPE AND COMBINATION VALVES - ASSEMBLY OVERVIEW
• EXHAUST MANIFOLD, FRONT EXHAUST PIPE WITH THREE WAY CATALYTIC CONVERTER (TWC) AND ATTACHMENTS
• FUNCTION OF E-GAS SYSTEM
• ENGINE CONTROL MODULE (ECM) (WITHOUT METAL ANTI-THEFT HOUSING), REPLACING
• ENGINE CONTROL MODULE (ECM) (WITH METAL ANTI-THEFT HOUSING), REPLACING
• SIGNAL FROM CLUTCH VACUUM VENT VALVE SWITCH, CHECKING
• SAFETY PRECAUTIONS
• RULES OF CLEANLINESS
• TECHNICAL DATA
• AIR FILTER, DISASSEMBLING AND ASSEMBLING
• MASS AIR FLOW (MAF) SENSOR, CHECKING
• ENGINE CONTROL MODULE (ECM), REPLACING
• COMPONENT LOCATIONS, OVERVIEW
• OXYGEN SENSOR HEATER FOR OXYGEN SENSORS BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING
• OXYGEN SENSOR AND OXYGEN SENSOR CONTROL BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING
• PARTS OF INTAKE MANIFOLD CHANGE - OVER, REMOVING AND INSTALLING
• THROTTLE VALVE CONTROL MODULE, REMOVING AND INSTALLING
• FUEL RAIL WITH FUEL INJECTORS, DISASSEMBLING AND ASSEMBLING
• FUEL PRESSURE REGULATOR AND RESIDUAL PRESSURE, CHECKING
• CHECKING SIGNAL AND GROUND WIRES OF MASS AIR FLOW (MAF) SENSOR
• VEHICLES WITH ENGINE CODE ATQ (121 -PIN ENGINE CONTROL MODULE -ECM-)
• CONTINUATION OF TEST IF INDICATION IS APPROX. -40 °C