Multiport Fuel Injection (mfi) - 4.2l v8 5v - Bbd Audi S6 C5

Safety precautions

Note the following points if testers and measuring instruments have to be used during a road test

To prevent injuries to persons and/or damage to the fuel injection and ignition system, the following must be noted

1. Always switch off the ignition before connecting or disconnecting injection or ignition system wiring or tester cables.
2. To run engine at starting speed without actually starting it (for example, in order to test compression), unplug connector from the output stages of the ignition coils and also the connectors on the injectors.
3. In the case of some tests, a malfunction may be recognized and stored by the control module. At the end of all tests and repairs, the Diagnostic Trouble Code (DTC) memory should be checked and, if necessary, erased.
4. Always switch off the ignition before washing the engine.
5. Always switch off the ignition before connecting or disconnecting the battery, otherwise the engine control module may be damaged.

When working on the fuel supply/injection system, carefully observe the following 6 cleanliness rules

1. Thoroughly clean all unions and the adjacent areas before disconnecting.
2. Place removed parts on a clean surface and cover. Use lint-free cloths.
3. Carefully cover or seal open components if repairs cannot be done immediately.
4. Only install clean components: Only remove replacement parts from packaging immediately prior to installation. Do not use parts that have been stored loose (e.g. in toolboxes etc.).
5. When the system is open: Do not work with compressed air if this can be avoided. Do not move the vehicle unless absolutely necessary.
6. Separated electrical connectors: Protect from dirt and moisture. Make sure connections are dry when attaching.

Technical Data (A6 models)

TECHNICAL DATA (A6 MODELS)

Technical Data (S6 models)

TECHNICAL DATA (S6 MODELS)

Component locations overview

The components A to G are not (Scheme 396)

1. Brake light switch -F- and brake pedal switch -F47- In footwell on pedal bracket near brake pedal
2. Data Link Connector (DLC) Located below the instrument cluster to the left of the steering column
3. Fuel pump (FP) relay -J17- In the micro-central electrics behind storage compartment on driver' side, relay position 4
4. Motronic Engine Control Module (ECM) power supply relay -J271- 3-compartment relay carrier in electrics box in plenum chamber, relay position 3
5. Throttle Position (TP) sensor -G79- and Sender -2- for accelerator pedal position -G185- In footwell on accelerator pedal (both are accommodated in one housing)
6. "MIL" warning lamp In instrument cluster. Description of lamp. See «MALFUNCTION INDICATOR LAMP (MIL) -K83-, FUNCTION»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__malfunction-indicator-lamp-mil-k83-function) .
7. "EPC" warning lamp In instrument cluster. Description of lamp. See «ELECTRONIC POWER CONTROL (EPC) WARNING LAMP -K132- (FOR ELECTRONIC THROTTLE), FUNCTION»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__electronic-power-control-epc-warning-lamp) .

Note. The following list refers to (Scheme 396).

1. Evaporative emission (EVAP) canister purge regulator valve -N80
2. 3-pin connector For knock sensor (KS) 1 -G61
3. 4-way connector For Oxygen Sensor Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S) Heater 1 -Z29- downstream of catalytic converter Bank 1
4. 4-way connector For Oxygen Sensor 2 Behind Three Way Catalytic Converter (TWC) -G131- and Oxygen Sensor (O2S) Heater -Z30- downstream of catalytic converter Bank 2
5. Mass Air Flow (MAF) sensor -G70- with Intake Air Temperature (IAT) sensor -G42
6. 4-way connector For Heated Oxygen Sensor -G39- and Oxygen Sensor (O2S) Heater -Z19- Bank 1
7. Valve 1 for camshaft adjustment -N205
8. Fuel pressure regulator
9. Engine Coolant Temperature (ECT) sensor -G62- On coolant pipe behind cylinder head, bank 1
10. Throttle valve control module -J338- With Throttle drive (power accelerator actuation) -G186-, angle sensor -1- for throttle drive (power accelerator actuation) -G187- and angle sensor -2- for throttle drive (power accelerator actuation) -G188
11. Secondary air injection (AIR) solenoid valve -N112
12. 4-way connector For Heated Oxygen Sensor (HO2S) 2 -G108- and Oxygen Sensor (O2S) 2 Heater -Z28- upstream of catalytic converter Bank 2
13. 3-pin connector For Engine Speed (RPM) sensor -G28
14. Camshaft Position (CMP) sensor 2 -G163- Cylinder bank 2
15. Secondary air injection (AIR) pump relay -J299- In electronic box in plenum chamber
16. Motronic Engine Control Module (ECM) -J220- In electronic box in plenum chamber
17. Ignition coils with output stages Cylinder bank 2
18. 3-pin connector For knock sensor (KS) 2 -G66
19. Valve 2 for camshaft adjustment -N208
20. Intake manifold changeover valve
21. Manifold intake changeover valve In S6 models Intake air switch-over valve -N335
22. Camshaft Position (CMP) sensor -G40- Cylinder bank 1
23. Ignition coils with output stages Cylinder bank 1
24. Secondary air injection (AIR) pump motor -V101- Underneath on right of longitudinal member

Wiring and component check with test box VAG 1598/31

Note. The test box VAG 1598/31 is designed in such a way that it can be connected simultaneously to the engine control module wiring harness and to the engine control module itself. This has the advantage that the electronic motor control system remains fully functional when the test box is connected (for example, for measuring signals when the engine is running). Whether the engine control module has to be additionally connected to the test box or not is described in the respective test procedures. Use the hand multimeter VAG 1526 or the multimeter VAG 1715 and the diode test lamp VAG 1527 or equivalent for the checks. To connect the test devices to the VAG 1598/31 test box, always use auxiliary cables from adapter set VAG 1594.

Connecting test box VAG 1598/31

1. Switch ignition off.
2. Remove cover of electronics box for control modules in plenum chamber.

Note. If the engine control module has a metal housing (anti-theft protection), the metal housing must be disconnected from the engine control module in order to connect the test box. Procedure. See Removing engine control module . Reinstall metal housing to control module on completion of repairs.

1. Carefully pry off retainer bar with a screwdriver -arrow-.
2. Release connectors on control module and disconnect.
3. Connect VAG 1598/31 test box to connector on wiring harness. Ground clamp -arrow- must be connected to Ground.

Note. Whether or not the engine control module has to be additionally connected to test box is described in the respective test procedures.

1. Perform test as described in appropriate repair procedures.

After installing the engine control module, perform the following operations

1. After reconnecting engine control module, perform adaptation of engine control module to throttle valve control module. See «THROTTLE VALVE CONTROL MODULE, ADAPTATION»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__throttle-valve-control-module-adaptation) .
2. In vehicles with automatic transmission, perform adaptation of kick down switch. See «Kick down switch point, checking»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__kick-down-switch-point-checking) .

Motronic engine control module (ECM) -J220-, replacing

The following procedure is for engine control modules which are not secured with a protective housing (anti-theft protection). The procedure for engine control modules with a metal housing is on. See REPLACING ENGINE CONTROL MODULES WHICH ARE SECURED WITH A PROTECTIVE HOUSING .

Note. When the engine control module is disconnected, the learned values are erased but the contents of the Diagnostic Trouble Code (DTC) memory remain intact.

Removing engine control module

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

The display on Vehicle Diagnostic, Testing and Information System VAS 5051 shows the control module identification and code -2-.

Scheme 396

1. Display and print out control module identification.
2. Compare code to coding versions. See «ENGINE CONTROL MODULE (ECM), CODING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__engine-control-module-ecm-coding) .
3. Switch ignition off.
4. Remove cover of protective housing for control modules.
5. Carefully pry off retainer bar with a screwdriver -arrow-.
6. Release connectors on engine control module and disconnect connectors.
7. Take out old engine control module and install new engine control module.

Installing engine control module

Installation is performed in the reverse sequence.

The following operations must be performed after installing the engine control module

1. Code new engine control module. See «ENGINE CONTROL MODULE (ECM), CODING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__engine-control-module-ecm-coding) .
2. Adapt immobilizer to engine control module: See «ADAPTATION AFTER REPLACING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/cruise-control-systems/#on-board-diagnostic-obd-2001-and-up__adaptation-after-replacing-engine-control-module) .
3. Adapt throttle valve control module -J338-. See «THROTTLE VALVE CONTROL MODULE, ADAPTATION»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__throttle-valve-control-module-adaptation) .
4. In vehicles with automatic transmission, perform adaptation of kick down switch. See «KICK DOWN SWITCH POINT, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__kick-down-switch-point-checking) .
5. In vehicles with cruise control (recognizable from steering column switch), this should be actuated in engine control module. See «ACTIVATING CRUISE CONTROL SYSTEM»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__activating-cruise-control-system) .
6. Check Diagnostic Trouble Code (DTC) memory and erase, if necessary. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__diagnostic-trouble-code-dtc-memory-checking) .

Activating cruise control system

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 397

1. Press "1" key twice for "Log-in procedure" function and confirm entry with Q key.

Indicated on display

Scheme 398

1. Enter code number 11463 and confirm entry with Q key.
2. Select address word "01" to control engine electronics control module.

Indicated on display

Scheme 399

Specified value: "G"

Deactivating cruise control system

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 400

1. Press "1" key twice for "Log-in procedure" function and confirm entry with Q key.

Indicated on display

Scheme 401

1. Enter code number 16167 and confirm entry with Q key.
2. Select address word "01" to control engine electronics control module.

Indicated on display

Scheme 402

Replacing engine control modules which are secured with a protective housing

Note. When the engine control module is disconnected, the learned values are erased but the contents of the Diagnostic Trouble Code (DTC) memory remain intact.

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

The display on V.A.S 5051 shows the control module identification code and code -2-.

Scheme 403

1. Display and print out control module identification.
2. Compare code to coding versions. See «ENGINE CONTROL MODULE (ECM), CODING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__engine-control-module-ecm-coding) .
3. Switch ignition off.
4. Remove cover of protective housing for control modules.
5. Carefully pry off retainer bar with a screwdriver -arrow-.

Note. Item -1- of illustration shows the engine control module with anti-theft protection housing.

To make access to connectors on the engine control module more difficult (anti-theft protection), engine control module -1- is secured to a metal housing -4- with a catch -2- and shear bolts -3-.

Scheme 404

The thread of shear bolts is coated with locking fluid, to additionally hinder removal of shear bolts.

In order to disconnect the connectors from the engine control module (e.g. when connecting test box or replacing engine control module), the engine control module must first be disconnected from the metal housing. This process is described on the following pages.

The following tools are required

1. Hot air blower -1- (from wiring harness repair set VAS 1978)
2. Clip-on nozzle -2- (also from wiring harness repair set VAS 1978)
3. Commercial gripper (self-grip pliers)

Procedure

1. Tilt engine control module with anti-theft protection housing in direction of engine compartment, so that catch (Item -2- in illustration) is visible. Place a clean cloth under engine control module with anti-theft protection housing.
2. Adjust settings on hot air blower as shown in illustration. Set potentiometer for temperature setting -2- at maximum heat output and the two-speed switch for air volume -3- to position 3.

The following operations will be concerned with heating the thread of the catch, into which the shear bolts are screwed. This will reduce the holding effect of the locking fluid on the thread of the shear bolts. The shear bolts may then be removed.

1. Direct nozzle -1- of hot air blower onto thread of catch, so that nozzle "encloses" thread. Nozzle can safely be allowed to contact upper end of metal housing.
2. Switch on hot air blower and heat thread for approx. 20 to 25 seconds.
3. Then grip bolt head -2- using gripper -1- and unscrew shear bolt in direction of arrow.

Note. The procedure for removing the second shear bolt is identical. Be particularly careful here, as this shear bolt is in the immediate vicinity of the control module connector.

1. Direct nozzle -1- of hot air blower onto thread of catch again, so that nozzle "encloses" thread. Nozzle can safely be allowed to contact upper end of metal housing.
2. Switch on hot air blower and heat thread for approx. 20 to 25 seconds.
3. Then grip bolt head -2- using gripper -1- and unscrew shear bolt in direction of arrow.

Engine control module can now be removed from metal housing.

1. Release connectors on engine control module and disconnect connectors.
2. Remove old engine control module and install new engine control module.

Installation is performed in reverse sequence. The engine control module must be re-installed with a metal housing. Use new shear bolts.

After installing a new engine control module, it is essential to carry out the following steps

1. Code new engine control module. See «ENGINE CONTROL MODULE (ECM), CODING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__engine-control-module-ecm-coding) .
2. Adapt immobilizer to engine control module. See «ADAPTATION AFTER REPLACING ENGINE CONTROL MOD»(/audi/s6/c5-1999-2004/remont/cruise-control-systems/#on-board-diagnostic-obd-2001-and-up__adaptation-after-replacing-engine-control-module) .

1. Adapt throttle valve control module -J338-. See «THROTTLE VALVE CONTROL MODULE, ADAPTATION»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__throttle-valve-control-module-adaptation) .
2. In vehicles with automatic transmission, perform adaptation of kick down switch. See «KICK DOWN SWITCH POINT, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__kick-down-switch-point-checking) .
3. In vehicles with cruise control (recognizable from steering column switch), this should be actuated in engine control module. See «ACTIVATING CRUISE CONTROL SYSTEM»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .
4. Check Diagnostic Trouble Code (DTC) memory and erase, if necessary. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__diagnostic-trouble-code-dtc-memory-checking) .

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 405

1. Press "1" key twice for "Log-in procedure" function and confirm entry with Q key.

Indicated on display

Scheme 406

1. Enter code number 11463 and confirm entry with Q key.
2. Select address word "01" to control engine electronics control module.

Indicated on display

Scheme 407

Specified value: "G"

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 408

1. Press "1" key twice for "Log-in procedure" function and confirm entry with Q key.

Indicated on display

Scheme 409

1. Enter code number 16167 and confirm entry with Q key.
2. Select address word "01" to control engine electronics control module.

Indicated on display

Scheme 410

Test conditions

1. No leaks in exhaust system
2. Coolant temperature at least 85 °C.
3. Electrical consumers switched off (radiator fan must not run during the check)
4. Air conditioner switched off
5. Pressure gauge not connected
6. Place selector lever in P or N position (vehicles with automatic transmission)

Checking idling speed

Note. The idling speed cannot be adjusted. The idling speed is tested during the basic setting of the engine. During the basic setting of the engine, the air conditioner compressor is automatically switched off and the EVAP canister purge regulator valve is closed.

1. Check Diagnostic Trouble Code (DTC) memory. DTC memory must be clear. If necessary, correct any malfunctions and erase DTC memory.
2. Switch engine off, then start up again. Perform road test and check DTC memory again to make sure it is clear.
3. Start engine and run at idling speed.
4. Switch off air conditioner.
5. Switch off rear window defroster.
6. Position selector lever in P or N position (vehicles with automatic transmission).

Indicated on display

Scheme 411

1. Press keys 0 and 4 for function "Introduction of basic setting" and confirm entry with Q key.

Indicated on display

1. Press keys 0, 5 and 6 for "display group number 56" and confirm entry with Q key.

Indicated on display: (1...4 = display zones)

Scheme 412

1. Check whether engine speed in display zone 1 (actual speed) is within permitted tolerance range (670 rpm to 850 rpm).

DISPLAY GROUP 56: IDLING STABILIZATION WHEN IDLING AT OPERATING TEMPERATURE

1. The engine speed in display zone 1 (actual speed) is the actual engine speed.
2. The engine speed in display zone 2 (specified speed) is a theoretical value calculated by the engine control module.
3. During idling, the engine control module always tries to adapt the actual engine speed to the specified engine speed.
4. This means that during idling the actual engine speed must always approximate the specified engine speed.
5. The display zones three and four are there for information but are irrelevant for checking the engine idling speed.

1. Press -> key.
2. Press keys 0 and 6 for "End output" function and press Q key to confirm entry.
3. If specification is not attained, check DTC memory again.
4. If DTC memory was erased, readiness code must be re-generated. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

If the idling speed is too high or too low or not smooth and there are no DTCs recorded in the DTC memory, perform the following tests marked with a dot

1. Check oxygen sensor learned values and oxygen sensor control. See «CHECKING OXYGEN SENSOR LEARNED VALUES AND OXYGEN SENSOR CONTROL»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-oxygen-sensor-learned-values-and) .
2. Check for unmetered air in intake system.
3. Check whether EVAP canister purge regulator valve is continuously open. See «EVAPORATIVE EMISSIONS (EVAP) SYSTEM»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .
4. Perform adaptation of throttle valve control module. See «THROTTLE VALVE CONTROL MODULE, ADAPTATION»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__throttle-valve-control-module-adaptation) .

Meaning of 5 digit readout of display group 56

MEANING OF 5 DIGIT READOUT OF DISPLAY GROUP 56

1. Fuel pump relay OK
2. Fuel pump OK
3. Fuel filter OK
4. Battery voltage at least 11 volts

Note. Fuel pressure regulator regulates fuel pressure as a function of intake pressure.

1. Briefly open fuel tank filler cap (to release pressure).
2. Cover pressurized screw connection with a cloth.
3. Open screw connection -arrow- and catch escaping fuel in a cloth.
4. Install pressure measuring device VAG 1318 together with adapters VAG 1318/6, 1318/7 between feed line and fuel manifold tube.
5. Open cut-off valve on pressure gauge. Lever points in direction of flow.

Note. The shut-off cock of the pressure measuring device should be open (lever facing in the direction of flow).

1. Start engine and run at idling speed.
2. Measure fuel pressure. Specified value: approx. 3.5 bar
3. Disconnect vacuum hose -arrow- from fuel pressure regulator.

Note. Replace pressure regulator if fuel emerges at the vacuum connection of the pressure regulator in the course of the following pressure test.

The fuel pressure should rise to approx. 4.0 bar.

If specification is not attained

1. Replace pressure controller as a test and repeat pressure test.
2. If specification is still not attained, check fuel pump/feed pipe for damage (e.g. crushing) and replace, if necessary.

If specified value is attained

1. Reconnect vacuum hose.
2. Switch ignition off.
3. Test for leaks and holding pressure by watching pressure drop on gauge. After 10 minutes the remaining pressure should be at least 3 bar.

If the holding pressure drops below 3.0 bar

1. Start engine and run at idling speed.
2. Allow pressure to build up, then switch off ignition. At same time close cut-off valve on pressure gauge VAG 1318 (valve lever at right angles to direction of flow).
3. Observe pressure drop on gauge.

If the pressure drops again, the following malfunctions are possible

1. Unions on pressure gauge after cut-off valve leaking
2. Fuel pressure regulator faulty
3. Injectors leaking

If the pressure does not drop, the following malfunctions are possible

1. Union between pressure gauge and fuel supply line leaking
2. Supply line leaking at fuel tank

1. Non-return valve in fuel pump leaking. See «FUEL PUMP (FP) -G6-, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#fuel-supply-system-all-engines) .

1. Fuel pressure OK

Removing fuel manifold tube

1. Remove engine compartment cover.
2. Remove connecting pipe between air cleaner housing and throttle valve body.
3. Disconnect vacuum hose from fuel pressure regulator.
4. Separate connectors for knock sensors and remove cable ties as necessary.
5. Disconnect solenoid valve for secondary air injection from fuel manifold tube.
6. Disconnect connectors from injectors and remove cable ties as necessary.
7. Unbolt fuel manifold from variable intake manifold and pull it upward and off intake manifold together with injectors.

Checking injectors for leaks

1. Place injector to be tested in a measuring glass from injection quantity tester VAG 1602.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Bridge contacts 1 and 65 on test box using test leads from adapter set VAG 1594 A (this creates a Ground connection to one side of fuel pump relay coil).
4. Switch ignition on.

Note. Once the ignition has been switched on, the fuel pump runs continuously even if the engine is not running. This is because with the ignition is switched on, the fuel pump relay receives its positive voltage supply via the engine electrics. The Ground voltage supply for the fuel pump relay comes via the cable bridge in the test box.

1. Check injectors for leaks (visual check). When fuel pump is running, only 1 or 2 drops a minute should escape from each injector.
2. If fuel loss is greater than this, switch off fuel pump (switch off ignition) and replace faulty injector.

Checking injection quantity

1. Place injector which is to be tested into measuring glass of injection quantity tester VAG 1602.
2. Connect one of injector contacts to engine Ground using a test cable and alligator clip from VAG 1594 A.
3. Connect second contact of injector with remote control V.A.G 1348/3A, adapter lead VAG 1348/3-2 and auxiliary cable to positive.
4. Switch ignition on. The fuel pump should run.
5. Activate remote control VAG 1348/3A for 30 seconds.
6. Perform measurements on all injectors.
7. Once all four injectors have been actuated, place measuring glasses on a level surface.

Specification per injector

INJECTION QUANTITY SPECIFICATION PER INJECTOR

If the specified result is not attained for all injectors

1. Check fuel pressure. See «FUEL PRESSURE REGULATOR AND HOLDING PRESSURE, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

If the specified results are not attained for one injector

1. Replace relevant injector.

Note. When checking the injection quantity, also check the spray pattern. The spray pattern should be the same for all the injectors.

Installation of the fuel manifold together with injectors is performed in the reverse sequence. The following points should be noted when installing

1. Replace the O-rings at all opened connections. (when replacing the front O-ring, make sure the plastic cap is not removed from the injector head. The O-ring must be pulled off over the plastic cap).
2. Coat the O-rings with clean engine oil.
3. Check to make sure that the retainer clamps are properly seated.

Electrical checks on injectors

1. Remove connector from the injector which is to be tested.
2. Connect hand-held multimeter to injector to measure resistance. Specified value: 13 to 16 ohms

Note. When the engine is at operating temperature the resistance of the injectors is increased by approx. 4... 6 ohms.

If specified value is not attained

1. Replace injector.

If specified value is attained

1. Check voltage supply. See «INJECTORS, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

Checking power supply

1. Remove connector from injector to be tested.
2. Connect diode test lamp for measuring voltage between Ground and socket 1 of connector.
3. Operate starter for a few seconds (engine can be allowed to start). Specified value: The diode test lamp should illuminate.

If the diode test lamp illuminates

1. Check wiring. See «CHECKING WIRING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-wiring) .

If the diode test lamp does not illuminate

1. Check wiring from socket 1 via injector fuse to fuel pump relay for continuity and, if necessary, correct open circuit. See appropriate System Wiring Diagram article.

Scheme 413

1. Switch ignition off.
2. Remove connector from injector to be tested.
3. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
4. Check for open circuit and short to positive or Ground in following wiring connection: FUEL INJECTOR CIRCUIT TEST: OPENS/SHORTS Cylinder 2-pin connector on wiring harness, socket Test box V.A.G 1598/31, socket 1 2 96 2 2 19 or 23 3 2 113 4 2 88 5 2 97 6 2 112 7 2 24 8 2 89
5. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.
6. If wiring is OK replace engine control module. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) and regenerate readiness code. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Fuel Pump (FP) relay -J17- and relay actuation, checking

Voltage is supplied to the fuel pump and some injection system components via the Fuel Pump (FP) relay -J17-.

The condition for the closing of the fuel pump relay is that the engine should be turning. i.e. the relay is only connected to earth (via the engine control module) when engine speed pulses are detected in the engine control module.

1. Battery voltage OK.

Functional testing of fuel pump relay

Note. Fuel pump relay is located in the micro central electrics underneath storage compartment on driver's side, relay position 4.

Scheme 414

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.
2. Start output Diagnostic Test Mode (DTM). See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) . Fuel pump relay should pick up and fuel pump should run.

If the relay does not respond

1. Check actuation of fuel pump relay. See «CHECKING ACTUATION OF FUEL PUMP RELAY»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-actuation-of-fuel-pump-relay) .

If the fuel pump does not run.

1. Check actuation of fuel pump and components. See «CHECKING ACTUATION OF FUEL PUMP AND COMPONENTS»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-actuation-of-fuel-pump-and) .

Checking actuation of fuel pump relay

1. Switch ignition off.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Connect together sockets 65 and 2 on the test box using an auxiliary cable from VAG 1594. Specified value: The fuel pump relay (relay position 4) must respond.

If the relay responds now, but not during output DTM

1. Replace engine control module. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .

If the relay does not respond

1. Remove fuel pump relay from relay base (relay position 4).
2. Connect hand-held multimeter to contact 19 of relay socket and Ground to measure voltage. Specified value: approx. battery voltage

If specified value is not attained

1. Check wiring connections. See appropriate System Wiring Diagram article.

If specified value is attained

1. Check for open circuit and short to positive or Ground in following wiring connection

FUEL PUMP RELAY CIRCUIT TEST: OPEN/SHORTS

Wire resistance: max. 1.5 Ohm

1. Correct any open/short circuit as necessary.

If no wiring malfunction is detected

1. Replace Fuel Pump relay -J17-.
2. Read readiness code. If DTC memory was erased, re-generate readiness code. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Checking actuation of fuel pump and components

1. Remove cover of fuses.
2. Remove fuses 28, 29 and 34.
3. Start output DTM. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .
4. Connect hand-held multimeter (voltage measurement range) between Ground and either left or right contact of following fuses (only fuse contact is live).

FUEL PUMP CIRCUIT TEST: VOLTAGE SUPPLY

If the specified values are not obtained

1. Check wiring connections. See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace Fuel Pump (FP) relay -J17-.
2. Re-insert all removed fuses.
3. Read readiness code. If DTC memory was erased, re-generate readiness code. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Motronic Engine Control Module (ECM) power supply relay -J271-, checking

Note. The Motronic Engine Control Module (ECM) power supply relay -J271- is located in a triple relay carrier in electronic box in plenum chamber, relay position 3.

Scheme 415

Check actuation of ECM power supply relay

1. Switch ignition off.
2. Remove Motronic Engine Control Module (ECM) power supply relay -J271- from triple relay carrier.
3. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
4. Check following wiring for an open circuit or short circuit ECM POWER SUPPLY RELAY CIRCUIT TEST: OPENS/SHORTS Test box V.A.G 1598/31, socket Power supply relay, contact 23 4 Wire resistance: max. 1.5 Ohm
5. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Check power supply for power supply relay. See «CHECK THE POWER SUPPLY»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__check-the-power-supply) .

Check the power supply

1. Switch ignition off.
2. Connect hand-held multimeter to contact 2 and 9 of relay socket and Ground to measure voltage. Specified value: approx. battery voltage

If the specified value is not achieved, test the supply voltage according to the wiring diagram.

See appropriate System Wiring Diagram article.

If the specified value is achieved, check the wiring connections between power supply relay and engine control module. See CHECKING WIRING BETWEEN POWER SUPPLY RELAY AND ENGINE CONTROL MODULE .

Checking wiring between power supply relay and engine control module

1. Check fuse (see wiring diagram) See appropriate System Wiring Diagram article.

If no malfunction is detected at the fuse.

1. Check following wiring for an open circuit or short circuit

ECM POWER SUPPLY CIRCUIT TEST

Wire resistance: max. 1.5 Ohm

1. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no malfunctions have been found in any of the above checks, replace Motronic Engine Control Module (ECM) power supply relay -J271

Check requirements

1. Fuse for engine control module OK See appropriate System Wiring Diagram article.
2. Battery voltage at least 11 V
3. Alternator OK

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 416

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 417

1. Press keys 0, 0 and 4 for "display group number 4" and confirm entry with Q key.

Indicated on display

Scheme 418

1. Check specified value for battery voltage in display zone 2

DISPLAY GROUP 4: BATTERY VOLTAGE WITH ENGINE IDLING

Evaluation of display group 4

EVALUATION OF DISPLAY GROUP 4

Checking voltage supply from terminal 15 and terminal 30

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Connect hand-held multimeter VAG 1526 (voltage range) to following sockets on test box.

Voltage supply terminal 15 with ignition on

VOLTAGE SUPPLY TERMINAL 15 WITH IGNITION ON

Voltage supply terminal 30 with ignition off

VOLTAGE SUPPLY TERMINAL 30 WITH IGNITION OFF

If the specified values are not obtained

1. Check wiring connections. See appropriate System Wiring Diagram article.

1. Coolant temperature at least 80 °C.
2. Electrical consumers switched off (radiator fan must not run during the check)
3. Air conditioner switched off
4. Fuse for MAF sensor OK See appropriate System Wiring Diagram article.

Checking function

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 419

1. Press keys 0 and 4 for function "Introduction of basic setting" and confirm entry with Q key.

Note. During basic setting, the Evaporative Emission (EVAP) canister purge regulator valve -N80- is closed and the air conditioning compressor is switched off by the engine control module.

Indicated on display

Scheme 420

1. Press keys 0, 0 and 2 for "display group number 2" and confirm entry with Q key.

Indicated on display

Scheme 421

1. Check specified results for recorded load.

DISPLAY GROUP 2: INTAKE AIR MASS AT IDLE AND OPERATING TEMPERATURE

If specified value is attained

1. Press -> key.
2. Press keys 0 and 6 for "End output" function and press Q key to confirm entry.
3. Switch ignition off.

Evaluation of display group 002

EVALUATION OF DISPLAY GROUP 002

EVALUATION OF DISPLAY GROUP 002

Checking voltage supply to MAF sensor

1. Disconnect connector from MAF sensor.
2. Connect hand-held multimeter for voltage measuring to socket 2 of connector and engine Ground.
3. Operate starter briefly. Specified value: approx. battery voltage

Note. Voltage supply to MAF sensor is from fuel pump relay.

If battery voltage is not present

1. Test wiring from socket 2 on connector via fuse to fuel pump relay for open circuit or short to Ground. Correct, if necessary. See appropriate System Wiring Diagram article.

If the specified value is achieved

1. Check Ground supply to engine control module. See «CHECKING GROUND CONNECTION»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-ground-connection) .

Checking Ground connection

1. Connect hand-held multimeter for voltage measuring to sockets 2 and 3 of connector.
2. Operate starter briefly. Specified value: approx. battery voltage

Note. Engine control module Ground is present at socket 3 of the connector.

If specified value is not attained

1. Check wiring connections. See «CHECKING WIRING TO MAF SENSOR»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-wiring-to-maf-sensor) .
2. Connect hand-held multimeter for voltage measuring to sockets 3 and 4 of connector.
3. Switch ignition on. Specified value: approx. 5 V.

If specified value is not attained

1. Check wiring connections. See «CHECKING WIRING TO MAF SENSOR»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-wiring-to-maf-sensor) .

Checking wiring to MAF sensor

Note. The signal wire is also checked during the wiring check.

Scheme 422

1. Connect test box VAG 1598/31 to wiring harness for engine control module; engine control module must not be connected. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check for open circuit and short to positive or Ground in following wiring connections: MAF SENSOR CIRCUIT TEST: OPENS/SHORTS Connector for MAF sensor -G70-, socket Test box V.A.G 1598/31 socket 3 27 4 53 5 (signal wire) 29 Wire resistance: max. 1.5 Ohm
3. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.
4. Check all wires for short to one another. MAF SENSOR CIRCUIT TEST: SHORT TO ONE ANOTHER Connector for MAF sensor -G70-, socket Test box VAG 1598/31 socket 3 53 and 29 4 27 and 29 5 (signal wire) 27 and 53 Specified value: infinite resistance (open circuit)
5. If voltage supply and wiring are OK, replace MAF sensor -G70-.
6. Read readiness code. If DTC memory was erased, re-generate readiness code. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Intake Air Temperature (IAT) sensor -G42-, checking

Installation location of sensor (common component: MAF sensor and intake air temperature sensor in air filter element). See COMPONENT LOCATIONS OVERVIEW .

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 423

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 424

1. Press keys 0, 0 and 4 for "display group number 4" and confirm entry with Q key.

Indicated on display: (1...4 = display zones)

Scheme 425

1. Check specified result for intake air temperature sensor (display zone 4)

DISPLAY GROUP 4: INTAKE AIR TEMPERATURE WITH ENGINE IDLING

Scheme 426

Scheme 427

1. Switch ignition off.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Disconnect connector to MAF sensor. See «COMPONENT LOCATIONS OVERVIEW»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__component-locations-overview) .
4. Check for shorts between two lines. IAT SENSOR CIRCUIT TEST: SHORTS 5-pin connector on wiring harness, socket Test box V.A.G 1598/31, socket 1 27 Specified value: infinity Ohm (no connection)
5. Check for open circuit and short to positive or Ground in following wiring connections: IAT SENSOR CIRCUIT TEST: OPENS/SHORTS 5-pin connector on wiring harness, socket Test box V.A.G 1598/31, socket 1 85 or 26 (according to model year) See appropriate System Wiring Diagram article. 3 27 Wire resistance: max. 1.5 Ohm
6. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace intake air temperature (IAT) sensor -G42- (common component: Mass Air Flow (MAF) sensor -G70- and intake air temperature (IAT) sensor -G42-).

Engine Coolant Temperature (ECT) sensor -G62-, checking

Installation location of engine coolant temperature sensor. See COMPONENT LOCATIONS OVERVIEW .

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 428

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 429

1. Press keys 0, 0 and 4 for "display group number 4" and confirm entry with Q key.

Indicated on display

Scheme 430

1. Check specified value for engine coolant temperature sensor in display zone 3

DISPLAY GROUP 4: COOLANT TEMPERATURE WITH ENGINE IDLING

Checking wiring

1. Switch ignition off.
2. Unplug connector from sensor.
3. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
4. Check wiring from 4 pin connector...
5. ... to engine control module for checking for open circuit and short to positive or Ground. ECT SENSOR CIRCUIT TEST: OPENS/SHORTS 4-pin connector on wiring harness, socket Test box VAG 1598/31, socket 3 108 4 93 Wire resistance: max. 1.5 Ohm
6. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace Engine Coolant Temperature (ECT) sensor -G62-.
2. Read readiness code. If DTC memory was erased, re-generate readiness code. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Function of oxygen sensor control

The oxygen sensors compare the oxygen content in the air with the residual oxygen content in the exhaust gas and send a voltage signal to the control module.

The voltage signal for "Mixture rich" (low level of residual oxygen) is between about 0.5 and 1.0 V (referenced to reference Ground).

The voltage signal for "Mixture weak" (high residual oxygen) is between about 0...0.5 V (in relation to reference Ground).

During the transition from "rich" to "lean" and vice versa (lambda = 1.0), there is a voltage jump from 0.5...1.0 V to 0...0.5 V or vice versa.

Because of the sharp voltage jump the oxygen sensor control cannot maintain a constant ideal mixture composition of lambda = 1.0. The system fluctuates continuously between "slightly too lean" and "slightly too rich".

Note. "Reference Ground" means predetermined Ground from engine control module If the voltage does not change or only changes slowly the following faults are possible: Slots or holes in sensor head are blocked. Oxygen sensor has been subjected to excessive thermal stress. Contact resistance in signal wire or Ground wire. Oxygen sensor too cold; oxygen sensor heating not working. Oxygen sensor damaged by contact spray or similar product (the contact spray is drawn into the sensor through the fine cavities in the electrical wiring as a result of thermal fluctuations and capillary effects). Oxygen sensor damaged by silicone vapors (the engine draws in traces of any silicone based sealants that may have been used. The silicone does not burn and damages the oxygen sensor).

Oxygen sensor control and Heated oxygen sensors -G39- and -G108- before catalytic converter, checking

Special tools and equipment

1. VAG 1526 A
2. VAG 1594 A
3. VAG 1598/31
4. VAS 5051 with VAS 5051/1 or
5. V.A.G 1551 with V.A.G 1551/3 A

Note. For specific malfunction search, it is possible to switch off the oxygen sensor control by selecting display group 99 "Basic setting" mode and to switch it on again by selecting display group 99 in "Read measured value block" mode. After selecting the display group 99 (whether in "Basic setting" or "Read measured value block" mode), it is possible to switch back and forth between the functions 04 "Basic setting" and 08 "Read measured value block" by pressing the keys 4 or 8 on V.A.G 1551. On leaving function 04 "Basic setting", the oxygen sensor control is automatically re-activated.

1. Perform road test and do not erase Diagnostic Trouble Code (DTC) memory.
2. Coolant temperature at least 85 °C.

Functional test

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 431

1. Press keys 0 and 4 for function "Introduction of basic setting" and confirm entry with Q key.

Note. During basic setting, the EVAP canister purge regulator valve -N80- is closed and the air conditioner compressor is switched off.

Indicated on display

Scheme 432

1. Press keys 0, 3 and 0 for "display group number 30" and confirm entry with Q key.

Indicated on display: (1...4 = display zones)

Scheme 433

1. Check oxygen sensor status (display zones 1 to 4).

Note. The "oxygen sensor status" indicates the condition of the oxygen sensor control and the oxygen sensors.

DISPLAY GROUP 30: OXYGEN SENSOR STATUS AT IDLE (COOLANT TEMPERATURE AT LEAST 85 °C)

Meaning of 3 digit readout of display group 30

MEANING OF 3 DIGIT READOUT OF DISPLAY GROUP 30

Checking oxygen sensor learned values and oxygen sensor control

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 434

1. Press keys 0 and 4 for function "Introduction of basic setting" and confirm entry with Q key.

Note. During basic setting, the Evaporative Emission (EVAP) canister purge regulator valve -N80- is closed and the air conditioner compressor is switched off.

Indicated on display

Scheme 435

1. Press keys 0, 3 and 3 for "display group number 33" and confirm entry with Q key.

Indicated on display: (1...4 = display zones)

Scheme 436

1. Check oxygen sensor control (display zones 1 to 4): DISPLAY GROUP 33: OXYGEN SENSOR CONTROL AT IDLE Display zones 1 2 3 4 Display group 33: oxygen sensor control at idle Display xx.x% x.xxx volts xx.x% x.xxx V Display oxygen sensor control bank 1 oxygen sensor voltage, bank 1 oxygen sensor control bank 2 oxygen sensor voltage, bank 2 Range min.: -25.0% max.: 25.0% min.: 0 V max.: 1.000 V min.: -25.0% max.: 25.0% min.: 0 V max.: 1.000 V Specified value In range -10.0...10.0% the value must be at least 2% In range 0.000...1.000 volts, the voltage must fluctuate In range -10.0...10.0% the value must be at least 2% In range 0.000...1.000 volts, the voltage must fluctuate Note: If the specification is not attained. See «IF SPECIFICATION IS NOT ATTAINED IN DISPLAY ZONE 1 OR DISPLAY ZONE 3, OR IF THE VALUE DOES NOT FLUCTUATE BY AT LEAST 2%»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__if-specification-is-not-attained-in) . If the specification is not attained, see evaluation. See «Evaluation of display group 33»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__evaluation-of-display-group-33) . If the specification is not attained. See «IF SPECIFICATION IS NOT ATTAINED IN DISPLAY ZONE 1 OR DISPLAY ZONE 3, OR IF THE VALUE DOES NOT FLUCTUATE BY AT LEAST 2%»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__if-specification-is-not-attained-in) . If the specification is not attained, see evaluation. See «Evaluation of display group 33»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__evaluation-of-display-group-33) .
2. Press C key.
3. Press keys 0, 3 and 2 for "display group number 32" and confirm entry with Q key.

Indicated on display: (1...4 = display zones)

Scheme 437

1. Check oxygen sensor control (display zones 1 to 4)

DISPLAY GROUP 32: OXYGEN SENSOR LEARNED VALUES AT IDLE

If specification is not attained in display zone 1 or display zone 3, or if the value does not fluctuate by at least 2%

1. Check oxygen sensor heating. See «OXYGEN SENSOR HEATING, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__oxygen-sensor-heating-checking) .
2. Check oxygen sensor signal wiring and actuation. See «OXYGEN SENSOR SIGNAL WIRING AND ACTUATION, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__oxygen-sensor-signal-wiring-and-actuation) .
3. Check intake system for leaks and correct unmetered air
4. Checking fuel pressure regulator. See «FUEL PRESSURE REGULATOR AND HOLDING PRESSURE, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .
5. Fuel return line kinked or blocked.
6. Press --> key.
7. Press keys 0 and 6 for the "End output" function and press Q key to confirm entry.
8. Switch ignition off.

Evaluation of display group 32

EVALUATION OF DISPLAY GROUP 32

EVALUATION OF DISPLAY GROUP 32

Evaluation of display group 33

EVALUATION OF DISPLAY GROUP 33

1. Coolant temperature at least 85 ° C.

Test sequence

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 438

1. Enter "04" to select "Start basic setting" and confirm with Q key.

Indicated on display

Scheme 439

1. Enter "034" for "display group number 034" and confirm entry with Q key.

Display readout

Scheme 440

1. Perform the test as soon as "Test ON" appears in display zone 4.

Note. This process can take a few minutes.

DISPLAY GROUP 034: DIAGNOSIS, OXYGEN SENSOR AGING, (BANK 1)

Note on display zone 2

Calculated value from engine speed and load.

Note on display zones 3 and 4

The period specifies the time between two voltage jumps in the oxygen sensor (e.g. rich - lean - rich) thereby providing a measurement basis for the aging status of the oxygen sensor. If the specified time is exceeded, display zone 4 indicates = B1-P1 NOK.

(cont.)

If specification in display zone 3 or 4 is not attained

1. Replace Heated Oxygen Sensor (HO2S) -G39-.

Test sequence for Heated Oxygen Sensor (HO2S) 2

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 441

1. Enter "04" to select "Start basic setting" and confirm with Q key.

Indicated on display

Scheme 442

1. Enter "035" for "display group number 035" and confirm entry with Q key.

Display readout

Scheme 443

1. Perform test as soon as "Test ON" appears in display zone 4.

Note. This process can take a few minutes.

DISPLAY GROUP 035: DIAGNOSIS, OXYGEN SENSOR AGING, (BANK 2)

Note on display zone 2

Calculated value from engine speed and load.

Note on display zones 3 and 4

The period specifies the time between two voltage jumps in the oxygen sensor (e.g. rich - lean - rich) thereby providing a measurement basis for the aging status of the oxygen sensor. If the specified time is exceeded, display zone 4 indicates = B1-P1 NOK.

If specification in display zone 3 or 4 is not attained

1. Replace Heated Oxygen Sensor (HO2S) 2 -G108-.

Oxygen sensor control and Oxygen Sensors (02S) -G130- and -G131- behind Three Way Catalytic Converter (TWC), checking

Special tools and equipment

1. VAG 1526 A
2. VAG 1594 A
3. VAG 1598/31
4. VAG 1788/10
5. VAS 5051 with VAS 5051/1 or
6. V.A.G 1551 with V.A.G 1551/3 A

Note. The oxygen sensor control after the catalytic converter is superior to the oxygen sensor control before the catalytic converter and is used as correction control. It corrects slight mixture changes (e.g. enriches) through the oxygen sensor before the catalytic converter, by maintaining the oxygen sensor control for a certain period (dwell time) at the upper / lower point. If the time is in the positive range (e.g. 50 ms), the mixture is made richer. If it is in the negative range (e.g. -50 ms), the mixture is made leaner.

1. Perform road test and do not erase DTC memory.
2. Coolant temperature at least 85 ° C.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 444

1. Enter "04" to select "Start basic setting" and confirm with Q key.

Note. During basic setting, the EVAP canister purge regulator valve -N80- is closed and the air conditioner compressor is switched off.

Indicated on display

Scheme 445

1. Enter "034" for "display group number 034" and confirm entry with Q key.

Display readout

Scheme 446

1. Set engine speed to 2800...3200 rpm using engine speed controller VAG 1788/10.

Perform the test as soon as an exhaust gas temperature above 250 °C is attained in display zone 2.

Note. This process can take a few minutes.

1. Press C key.
2. Set engine speed to 1800...2400 RPM using engine speed controller VAG 1788/10.

Indicated on display

Scheme 447

1. Enter "030" for "display group number 030" and confirm entry with Q key.

Indicated on display

Scheme 448

1. Check oxygen sensor status for oxygen sensor after catalytic converter in display zones 2 and 4.

Note. The "oxygen sensor status" indicates the condition of the oxygen sensor control and the oxygen sensors.

DISPLAY GROUP 030: OXYGEN SENSOR STATUS AT IDLE

Note. The oxygen sensor control of oxygen sensor after catalytic converter (bank 1-sensor 2 and bank 2-sensor 2) is not active without engine load. The first digit of the 3-digit display (heating) fluctuates between 0 and 1. The third digit of the 3-digit display (oxygen sensor control) fluctuates between 0 and 1.

MEANING OF 3 DIGIT READOUT OF DISPLAY GROUP 30

1. Press C button.

Indicated on display

Scheme 449

1. Enter "043" for "display group number 043" and confirm entry with Q key.

Indicated on display

Scheme 450

1. Check specified value in display zone 4.

DISPLAY GROUP 043: HEATED OXYGEN SENSOR (HO2S) AGING DOWNSTREAM OF CATALYTIC CONVERTER (BANK 1)

If specified value "B1-S2 OK" is obtained

1. Press C button.
2. Enter "044" for "display group number 044" and confirm entry with Q key.

DISPLAY GROUP 044: HEATED OXYGEN SENSOR (HO2S) AGING AFTER CATALYTIC CONVERTER (BANK 2)

If specified value "B2-S2 OK" is obtained

1. Press C button.

Checking oxygen sensor control after catalytic converter

1. Perform a road test lasting at least 10 minutes.

Indicated on display

Scheme 451

1. Enter "037" for "display group number 037" and confirm entry with Q key.

Display readout

Scheme 452

1. Check oxygen sensor voltage in display zone 2.
2. Check dwell time between oxygen sensor 1 before catalytic converter and oxygen sensor 2 after catalytic converter in display zone 3 and diagnosis result in display zone 4.

DISPLAY GROUP 037: DIAGNOSIS, OXYGEN SENSOR CONTROL SYSTEM (BANK 1)

Note on display zone 3

The oxygen sensor control after the catalytic converter is superior to the oxygen sensor control before the catalytic converter and is used as a guidance control. It corrects slight rich / lean mixture changes in the oxygen sensor before catalytic converter, by maintaining the oxygen sensor control before catalytic converter at the upper / lower point for a certain period of time (dwell time). If the time is in the positive range (e.g. 50 ms), the mixture is made richer. If it is in the negative range (e.g. -50 ms), the mixture is made leaner.

1. Press C key.
2. Press keys 0, 3 and 8 for "display group number 38" and confirm entry with Q key.

Indicated on display: (1...4 = display zones)

Scheme 453

DISPLAY GROUP 038: OXYGEN SENSOR CONTROL SYSTEM DIAGNOSIS (BANK 2)

Note on display zone 3

The oxygen sensor control after the catalytic converter is superior to the oxygen sensor control before the catalytic converter and is used as a guidance control. It corrects slight rich / lean mixture changes in the oxygen sensor before catalytic converter, by maintaining the oxygen sensor control before catalytic converter at the upper / lower point for a certain period of time (dwell time). If the time is in the positive range (e.g. 50 ms), the mixture is made richer. If it is in the negative range (e.g. -50 ms), the mixture is made leaner.

Evaluation of display groups 037 and 038

EVALUATION OF DISPLAY GROUPS 037 AND 038

If specification in display zone 3 or 4 is not attained

1. Check for air leak at exhaust or catalytic converter (check screw clamps and exhaust for damage)
2. Replace appropriate oxygen sensor "before" catalytic converter.

Oxygen sensor heating, checking

Note. The oxygen sensor heating circuit is monitored by the On Board Diagnostic (OBD) system, checking Diagnostic Trouble Code (DTC) memory. See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING .

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 454

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 455

1. Press keys 0, 4 and 1 for "display group number 41" and confirm entry with Q key.

Indicated on display

Scheme 456

1. Check resistance of oxygen sensor heating.

DISPLAY GROUP 41: OXYGEN SENSOR HEATING, BANK 1 AT IDLING SPEED

1. Press C key.
2. Press keys 0, 4 and 2 for "display group number 42" and confirm entry with Q key.

DISPLAY GROUP 42: OXYGEN SENSOR HEATING, BANK 2 AT IDLING SPEED

If specified value is not attained

1. Check voltage supply to oxygen sensor heating. See «CHECKING VOLTAGE SUPPLY FOR OXYGEN SENSOR HEATING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-voltage-supply-for-oxygen-sensor) .
2. Check oxygen sensor signal wiring and actuation. See «OXYGEN SENSOR SIGNAL WIRING AND ACTUATION, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__oxygen-sensor-signal-wiring-and-actuation) .

Checking voltage supply for oxygen sensor heating

Installation locations of 4-pin connectors for oxygen sensors. See COMPONENT LOCATIONS OVERVIEW .

1. Check fuse for oxygen sensor heating. See appropriate System Wiring Diagram article.
2. Disconnect 4-pin connector of relevant oxygen sensor.
3. Using leads from VAG 1594, connect hand-held multimeter (voltage measurement range) to sockets 1 (positive) and 2 (Ground).
4. Operate starter briefly. Specified value: approx. battery voltage

If no voltage is present

1. Using leads from VAG 1594, connect hand-held multimeter (voltage measurement range) to socket 1 (positive) and vehicle Ground.
2. Operate starter briefly. Specified value: approx. battery voltage

If no voltage is present

1. Check wiring from socket 1 of relevant oxygen sensor connector on wiring harness via fuse to fuel pump relay for open circuit or short.

See appropriate System Wiring Diagram article.

If the power supply is OK

1. Using leads from VAG 1594, connect hand-held multimeter (voltage measurement range) to socket 2 (Ground actuation from engine control module) and battery positive.
2. Start engine. Specified value: approx. battery voltage, fluctuating

Note. At certain operating points, the engine control module "cycles" the Ground for the oxygen sensor heating. This means that at these points, the Ground is continuously switched on and off. For this reason, the voltage reading on the tester may fluctuate.

1. Switch ignition off.

If no voltage is present

1. Connect test box V.A.G 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check for open circuit in following wiring connections

Heated Oxygen Sensor (HO2S) -G39

HEATED OXYGEN SENSOR (HO2S) -G39- TEST REFERENCE

Heated Oxygen Sensor (HO2S) 2 -G108

HEATED OXYGEN SENSOR (HO2S) 2 -G108- TEST REFERENCE

Oxygen Sensor (O2S) behind TWC -G130

OXYGEN SENSOR (O2S) BEHIND TWC -G130- TEST REFERENCE

Oxygen Sensor (O2S) 2 behind TWC -G131

OXYGEN SENSOR (O2S) 2 BEHIND TWC -G131- TEST REFERENCE

Wire resistance: max. 1.5 Ohm

See appropriate System Wiring Diagram article.

If wiring connections are OK

1. Replace appropriate oxygen sensor.
2. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Oxygen sensor signal wiring and actuation, checking

Note. The oxygen sensor signal is monitored by the On Board Diagnostic (OBD) system.

1. Check DTC memory. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__diagnostic-trouble-code-dtc-memory-checking) .
2. If a DTC related to oxygen sensor is displayed and oxygen sensor heating is OK unplug connector for relevant oxygen sensor. Installation locations of 4-pin connectors for oxygen sensors. See «COMPONENT LOCATIONS OVERVIEW»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__component-locations-overview) .
3. Check voltage by connecting hand-held multimeter VAG 1526 (measuring range 2 V) between sockets 3 and 4 of plug on wiring harness.
4. Switch ignition on. Specified value: 450 +/- 50 mV.

If specified value is not attained

1. Check oxygen sensor wires: Heated Oxygen Sensor (HO2S) -G39-. See «Checking oxygen sensor wiring, Heated Oxygen Sensor (HO2S) -G39»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) . Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-. See «CHECKING OXYGEN SENSOR WIRING, OXYGEN SENSOR (O2S) BEHIND THREE WAY CATALYTIC CONVERTER (TWC) -G130»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-oxygen-sensor-wiring-oxygen-sensor) . Heated Oxygen Sensor (HO2S) 2 -G108-. See «CHECKING OXYGEN SENSOR WIRING, HEATED OXYGEN SENSOR (HO2S) 2 -G108»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-oxygen-sensor-wiring-heated-oxygen) . Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-. See «Checking oxygen sensor wiring, Oxygen Sensor (O2S) 2 -G131- Behind Three Way Catalytic Converter (TWC)»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-oxygen-sensor-wiring-oxygen-sensor) .

If specified value is attained

1. Replace oxygen sensor.

Scheme 457

Scheme 458

Scheme 459

1. Unplug 4-pin connector (black) to -G39-.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Test for open circuit in following wiring connections. HO2S -G39- CIRCUIT TEST: OPENS Connector on wiring harness, socket Test box VAG 1598/31 socket 3 51 4 70 Wire resistance: max. 1.5 Ohm See appropriate System Wiring Diagram article.
4. Also test wires on 4-pin connection for shorts between them. HO2S -G39- CIRCUIT TEST: SHORTS Connector on wiring harness, socket Test box VAG 1598/31 socket 4 51 Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.
5. Test screen wiring for short to oxygen sensor wiring. HO2S -G39- CIRCUIT TEST: SHORT TO HO2S WIRING Connector on wiring harness, socket Test box VAG 1598/31 socket 4 32 or 2 See appropriate System Wiring Diagram article. 3 32 or 2 See appropriate System Wiring Diagram article. Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .

Checking oxygen sensor wiring, Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130

Installation location of 4-pin connector for oxygen sensor. See COMPONENT LOCATIONS OVERVIEW .

Scheme 460

1. Unplug 4-pin connector for -G130-.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Test for open circuit in following wiring connections. HO2S -G130- CIRCUIT TEST: OPENS Connector on wiring harness, socket Test box VAG 1598/31 socket 3 68 4 69 Wire resistance: max. 1.5 Ohm See appropriate System Wiring Diagram article.
4. Also test wires on 4-pin connector for shorts between them. HO2S -G130- CIRCUIT TEST: SHORTS Connector on wiring harness, socket Test box VAG 1598/31 socket 4 68 Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.
5. Test screen wiring for short to oxygen sensor wiring. HO2S -G130- CIRCUIT TEST: SHORT TO HO2S WIRING Connector on wiring harness, socket Test box VAG 1598/31 socket 4 32 or 2 See appropriate System Wiring Diagram article. 3 32 or 2 See appropriate System Wiring Diagram article. Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .

Checking oxygen sensor wiring, Heated Oxygen Sensor (HO2S) 2 -G108

Installation location of 4-pin connector for oxygen sensor. See COMPONENT LOCATIONS OVERVIEW .

Scheme 461

1. Unplug 4-pin connector (black) to -G108-.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Test for open circuit in following wiring connections. HO2S -G108- CIRCUIT TEST: OPENS Connector on wiring harness, socket Test box VAG 1598/31 socket 3 12 4 13 Wire resistance: max. 1.5 Ohm See appropriate System Wiring Diagram article.
4. Also test wires on 4-pin connector for shorts between them. HO2S -G108- CIRCUIT TEST: SHORTS Connector on wiring harness, socket Test box VAG 1598/31 socket 4 12 Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.
5. Test screen wiring for short to oxygen sensor wiring. CHO2S -G108- CIRCUIT TEST: SHORT TO HO2S WIRING Connector on wiring harness, socket Test box VAG 1598/31 socket 4 32 or 2 See appropriate System Wiring Diagram article. 3 32 or 2 See appropriate System Wiring Diagram Electrical Component Locator article. Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .

Checking oxygen sensor wiring, Oxygen Sensor (O2S) 2 -G131- Behind Three Way Catalytic Converter (TWC)

Installation location of 4-pin connector for oxygen sensor. See COMPONENT LOCATIONS OVERVIEW .

Scheme 462

1. Disconnect 4-pin connector for -G131-.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Test for open circuit in following wiring connections. HO2S -G131- CIRCUIT TEST: OPENS Connector on wiring harness, socket Test box VAG 1598/31 socket 3 10 4 11 Wire resistance: max. 1.5 Ohm See appropriate System Wiring Diagram article.
4. Also test wires on 4-pin connector for shorts between them. HO2S -G131- CIRCUIT TEST: SHORTS Connector on wiring harness, socket Test box VAG 1598/31 socket 4 10 Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.
5. Test screen wiring for short to oxygen sensor wiring. HO2S -G131- CIRCUIT TEST: SHORT TO HO2S Connector on wiring harness, socket Test box VAG 1598/31 socket 4 See appropriate System Wiring Diagram article. 3 See appropriate System Wiring Diagram article. Specified value: infinite resistance (open circuit) See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .

Removing oxygen sensors before catalytic converter

1. Disconnect connector of relevant oxygen sensor before catalytic converter from cylinder bank 1 and cylinder bank 2 (Installation location. See «COMPONENT LOCATIONS OVERVIEW»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__component-locations-overview) ).
2. Remove cable wiring of oxygen sensors after catalytic converter. See «REMOVING OXYGEN SENSORS AFTER CATALYTIC CONVERTER.»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .
3. Remove left or right front exhaust pipe with catalytic converter. See «FRONT EXHAUST PIPE WITH THREE WAY CATALYTIC (TWC) CONVERTER (LEFT SIDE), REMOVING AND INSTALLING»(/audi/s6/c5-1999-2004/remont/exhaust/#exhaust-system-42l-v8-5v-art-awn-bbd__front-exhaust-pipe-with-three-way) and «FRONT EXHAUST PIPE WITH CATALYTIC CONVERTER, REMOVING AND INSTALLING (RIGHT SIDE)»(/audi/s6/c5-1999-2004/remont/exhaust/#exhaust-system-42l-v8-5v-art-awn-bbd__front-exhaust-pipe-with-catalytic-converter) .
4. Remove relevant oxygen sensor using special tool 3337/9.

Notes on installation of oxygen sensors. See WHEN INSTALLING, NOTE THE FOLLOWING POINTS .

Scheme 463

1. Disconnect connector of relevant oxygen sensor after catalytic converter from cylinder bank 1 and cylinder bank 2 (Installation location. See «COMPONENT LOCATIONS OVERVIEW»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__component-locations-overview) ).
2. If necessary remove air intake pipe -arrow- between air cleaner and throttle valve unit.
3. Remove hose -1- from air filter by rotating it in direction of arrow. (Scheme 504)
4. Disconnect bracket from EVAP canister purge regulator valve -2- from air filter box. (Scheme 504)
5. Disconnect connector from Mass Air Flow sensor -3-. (Scheme 504)
6. Unscrew bolt -arrow- and remove air filter box together with Mass Air Flow sensor and intake pipe.
7. Remove left or right front exhaust pipe with catalytic converter. See «FRONT EXHAUST PIPE WITH THREE WAY CATALYTIC (TWC) CONVERTER (LEFT SIDE), REMOVING AND INSTALLING»(/audi/s6/c5-1999-2004/remont/exhaust/#exhaust-system-42l-v8-5v-art-awn-bbd__front-exhaust-pipe-with-three-way) and «FRONT EXHAUST PIPE WITH CATALYTIC CONVERTER, REMOVING AND INSTALLING (RIGHT SIDE)»(/audi/s6/c5-1999-2004/remont/exhaust/#exhaust-system-42l-v8-5v-art-awn-bbd__front-exhaust-pipe-with-catalytic-converter).
8. Attach a binding wire to connectors for oxygen sensors after catalytic converter (to facilitate insertion of wiring connections above transmission).
9. Remove rear heat shield -A- above propshaft.
10. Unbolt heat shield -B- of propshaft from Torsen differential cover -arrows-.
11. Mark position of propshaft (due to misalignment).
12. Unbolt prop shaft from flange.
13. Secure propshaft with wire at floor to vehicle. See «WHEN INSTALLING, NOTE THE FOLLOWING POINTS»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__when-installing-note-the-following-points).
14. Disconnect subframe.
15. Remove four hex bolts -1-.
16. Remove hex bolts -2- and lower subframe at rear.

Tightening torques

1. Torque for hex bolt -1-: 75 Nm
2. Torque for hex bolt -2-: always replace and tighten to 110 Nm plus additional 90° turn.

1. Open all cable ties at transmission for wiring connections of rear oxygen sensors.
2. Move wiring connections toward rear.
3. Remove relevant oxygen sensor using special tool 3337/9.

When installing, note the following points

Note. When installing, the oxygen sensor wire must be secured in exactly the same position as before in order to avoid contact between the wire and the exhaust pipe. The screw thread on the oxygen sensor is coated with assembly paste. This paste must not be allowed to penetrate the openings on the sensor. Tightening torque: 55 Nm. It is essential that the locking fluid remaining in the threads in the flange shafts on the transmission and rear final drive is cleaned out after removing the propshaft. Otherwise there is a danger that the new bolts will seize when they are screwed in and then shear if they have to be removed later. The threaded holes can be cleaned with a thread tap. Always replace propshaft bolts (self-locking).

Intake manifold change-over, checking (A6 models)

Only perform the test when there is a lack in performance or a DTC was registered.

The change-over of the intake manifold from the long to the short intake path is dependent on speed.

Intake manifold change-over, function

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control unit 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 464

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 465

1. Press keys 0, 9 and 5 for "display group number 95" and confirm entry with Q key.

Indicated on display

Scheme 466

Scheme 467

1. Check display values for intake manifold change-over. DISPLAY GROUP 95: INTAKE MANIFOLD CHANGE-OVER AT IDLING SPEED (A6) Display zones 1 2 3 4 Display group 95: Intake manifold change-over at idling speed Display xxx rpm x.x% xxx.x ° C IMC-V OFF Display Engine speed (in steps of 40 rpm) Load Coolant temperature Intake manifold change-over function Range min.: 550 rpm max.: 7200 rpm min.: 0.00% max.: 110.00% IMC-V OFF Step 1 Step 2 Specified value 670...820 rpm 14...24% 80.0...105.0 °C IMC-V OFF Note: Both vacuum units must be actuated
2. Check display in display zone 4. Specified value: "IMC-V OFF"
3. Increase engine speed to following speed to initiate intake manifold change-over. ENGINE SPEED AND VACUUM UNIT (A6) Engine speed Vacuum unit approx. 3400 rpm Stage 1 lower vacuum unit approx. 5300 rpm Stage 2 upper vacuum unit DISPLAY GROUP 95: INTAKE MANIFOLD CHANGE-OVER WITH VEHICLE BEING DRIVEN (A6) Display zones 1 2 3 4 Display group 95: Intake manifold change-over with vehicle being driven Display xxxx rpm xx.xx% xxx.x ° C Stage 1 or 2 Display Engine speed (in steps of 40 rpm) Load Coolant temperature Intake manifold change-over Range min.: 550 rpm max.: 7200 rpm min.: 0.00% max.: 110.00% IMC-V OFF Step 1 Step 2 Specified value xxxx rpm xx.xx% 80.0...105.0 °C Stage 1 or 2 Note: Observe change-over procedure at vacuum units (installation location is at front of intake pipe)
4. Check whether correct vacuum unit is actuated with relevant speed.

If "stage 1 or 2" is displayed but the intake manifold change-over is not initiated (vacuum units must not be actuated) check the following components

1. Check solenoid valves for intake manifold change-over. See «INTAKE MANIFOLD CHANGE-OVER VALVE -N156- AND INTAKE MANIFOLD TUNING (IMT) VALVE 2 -N261-, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__intake-manifold-change-over-valve-n156-and) .

Intake Manifold Change-Over valve -N156- and Intake Manifold Tuning (IMT) valve 2 -N261-, checking

1. Run engine at idling speed for 2 or 3 minutes to build up vacuum pressure.
2. Switch engine off.
3. Switch ignition on.
4. Perform output Diagnostic Test Mode (DTM) and activate intake manifold change-over valves. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 468

Indicated on display

Scheme 469

Solenoid valves should click (clicking can be heard and felt). After 1 minute output DTM is terminated.

If one of the solenoid valves does not click

1. Switch ignition off.
2. Unplug connector from relevant intake manifold change-over valve.
3. Measure resistance between solenoid valve contacts using VAG 1526. Specified value: 25...35 Ohms
4. If specified value is not achieved, replace intake manifold change-over valve or IMT valve 2.

If specification is attained, check voltage supply. See CHECKING VOLTAGE SUPPLY OF INTAKE MANIFOLD CHANGE-OVER VALVE/IMT VALVE 2 .

Checking voltage supply of intake manifold change-over valve/IMT valve 2

1. Connect diode test lamp VAG 1527 between engine Ground and socket 1 (positive) on connector using cables from adapter set VAG 1594.
2. Operate starter briefly. Diode test lamp should illuminate.

If the diode test lamp does not illuminate

1. Check fuse for intake manifold change-over valve/IMT valve 2. See appropriate System Wiring Diagram article.

If the fuse is OK

1. Check for open circuit and short in wiring between fuel pump relay and socket 1 on connector via fuse for intake manifold change-over valve/IMT valve 2. See appropriate System Wiring Diagram article.

If the voltage supply is OK, check actuation. See CHECKING ACTUATION OF INTAKE MANIFOLD CHANGE-OVER VALVE/IMT VALVE 2 .

1. Re-insert fuel pump relay and fuse.

Checking actuation of intake manifold change-over valve/IMT valve 2

1. Connect diode test lamp VAG 1527 between sockets 1 and 2 on connector for intake manifold change-over valve/IMT valve 2 using cables from adapter set VAG 1594.
2. Perform output DTM and actuate intake manifold change-over valve or IMT valve 2. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 470

Indicated on display

Scheme 471

If the diode test lamp does not flash or is continuously lit

1. Check wiring. See «Checking wiring»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check following wiring connections for open circuit and short circuit to positive or Ground. INTAKE MANIFOLD CHANGE-OVER VALVE/IMT VALVE 2 CIRCUIT TEST: OPENS/SHORTS (A6) Connector for intake manifold change-over valve socket Test box VAG 1598/31 socket 2 48 Connector for intake manifold tuning valve 2 socket Test box VAG 1598/31 socket 2 45 Wire resistance: max. 1.5 Ohm See appropriate System Wiring Diagram article.
3. If wiring is OK replace engine control module. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .
4. Check intake manifold change-over again for function. See «INTAKE MANIFOLD CHANGE-OVER, CHECKING (A6 MODELS)»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__intake-manifold-change-over-checking-a6-models) .
5. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Checking solenoid valves for obstruction and leaks

1. Remove intake manifold change-over valve or IMT valve 2.
2. Disconnect connector from valve to be checked.
3. Connect one contacts on valve to engine Ground using test leads and alligator clamp from VAG 1594 A.
4. Connect second contact of valve with remote control VAG 1348/3A, adapter lead VAG 1348/3-2 and auxiliary cable.
5. Operate remote control VAG 1348/3A.
6. Check by blowing into connection whether valve opens correctly.

If a solenoid valve does not open.

1. Replace intake manifold change-over valve or IMT valve 2.

If none of the checks already performed indicate a malfunction

1. Re-install relevant valve.
2. Check vacuum system for leaks. See «CHECKING VACUUM SYSTEM FOR LEAKS»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-vacuum-system-for-leaks) .

Checking vacuum system for leaks

1. Disconnect vacuum hoses from relevant vacuum unit for intake manifold change-over.
2. Connect hand vacuum pump VAG 1390 to vacuum unit.
3. Operate hand pump and check whether change-over function is working.
4. Check vacuum unit for leaks. (Vacuum unit should not return to rest position until hand pump is vented to atmosphere.)

If vacuum unit retracts

1. If necessary, replace vacuum unit.

If the vacuum unit does not have any leaks check all vacuum hoses for leaks.

Intake manifold change-over, checking (S6 models)

The first stage of the intake manifold change-over is omitted with all S6 models .

Only perform the test when there is a lack in performance or a DTC was registered.

The change-over of the intake manifold from the long to the short intake path is dependent on speed.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control unit 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 472

1. Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 473

1. Press keys 0, 9 and 5 for "display group number 95" and confirm entry with Q key.

Indicated on display

Scheme 474

1. Check display values for intake manifold change-over. DISPLAY GROUP 95: INTAKE MANIFOLD CHANGE-OVER AT IDLING SPEED (S6) Display zones 1 2 3 4 Display group 95: Intake manifold change-over at idling speed Display xxx rpm x.x% xxx.x ° C IMC-V OFF Display Engine speed (in steps of 40 rpm) Load Coolant temperature Intake manifold change-over function Range min.: 550 rpm max.: 7200 rpm min.: 0.00% max.: 110.00% IMC-V OFF IMC-V ON Specified value 670...820 rpm 14...24% 80.0...105.0 ° C IMC-V OFF Note: Both vacuum units must be actuated
2. Check display in display zone 4.

Specified value: "IMC-V OFF"

Specification for display zone 4

Scheme 475

"IMC-V OFF" vacuum units tightened

1. Increase engine speed to approx. 5400 rpm to initiate intake manifold change-over. DISPLAY GROUP 95: INTAKE MANIFOLD CHANGE-OVER WITH VEHICLE BEING DRIVEN (S6) Display zones 1 2 3 4 Display group 95: Intake manifold change -over with vehicle being driven Display xxxx rpm xx.xx% xxx.x ° C IMC-V ON Display Engine speed (in steps of 40 rpm) Load Coolant temperature Intake manifold change -over function Range min.: 550 rpm max.: 7200 rpm min.: 0.00% max.: 110.00% IMC-V OFF IMC-V ON Specified value xxxx rpm xx.xx% 80.0...105.0 °C IMC-V ON Note
2. Check whether vacuum units are actuated.

If "SU-V ON" is displayed but the intake manifold change -over is not initiated (vacuum units must not be actuated) check the following component

1. Check solenoid valves for intake manifold change-over. See «INTAKE MANIFOLD CHANGE-OVER VALVE -N156- AND INTAKE MANIFOLD TUNING (IMT) VALVE 2 -N261-, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__intake-manifold-change-over-valve-n156-and) .

Intake manifold change-over valve -N156-, checking

1. Run engine at idling speed for 2 or 3 minutes to build up vacuum pressure.
2. Switch engine off.
3. Switch ignition on.
4. Perform output Diagnostic Test Mode and actuate intake manifold change-over valve. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 476

Valve should click (clicking can be heard and felt). After 1 minute output DTM is terminated.

If solenoid valve does not click

1. Switch ignition off.
2. Disconnect connector from relevant solenoid valve for intake manifold change-over.
3. Measure resistance between contacts on solenoid valve using VAG 1526. Specified value: 25...35 Ohms
4. If measured value is not as specified, replace solenoid valve for intake manifold change-over.

If the specified value is achieved, check the voltage supply.

Checking voltage supply of intake manifold change-over valve

1. Connect diode test lamp V.A.G 1527 between engine Ground and socket 1 (positive) on connector using cables from adapter set VAG 1594.
2. Operate starter briefly. Diode test lamp should illuminate.

If the diode test lamp does not illuminate

1. Check fuse for solenoid valve for intake manifold change-over. See appropriate System Wiring Diagram article.

If the fuse is OK

1. Check for open circuit and short in wiring between fuel pump relay and socket 1 on connector via fuse for intake manifold change-over solenoid valve. See appropriate System Wiring Diagram article.

If the voltage supply is OK, check actuation.

1. Re-insert fuel pump relay and fuse.

Checking actuation of intake manifold change-over valve

1. Connect diode test lamp VAG 1527 between sockets 1 and 2 on connector for intake manifold change-over valve using cables from adapter set VAG 1594.
2. Perform output Diagnostic Test Mode (DTM) and actuate solenoid valve for intake manifold change-over. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 477

If the diode test lamp does not flash or is continuously lit

1. Check wiring. See «CHECKING WIRING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

1. Connect test box VAG 1598/31 to wiring harness for engine control unit; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .

Check the following wiring connections for open circuit and short circuit to positive or Ground.

INTAKE MANIFOLD CHANGE-OVER VALVE CIRCUIT TEST: OPENS/SHORTS (S6)

Wire resistance: max. 1.5 Ohm

See appropriate System Wiring Diagram article.

If wiring is OK

1. Replace engine control module. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .
2. Check intake manifold change-over again for function. See «INTAKE MANIFOLD CHANGE-OVER, CHECKING (A6 MODELS)»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__intake-manifold-change-over-checking-a6-models) .
3. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Checking valve for obstruction and leaks

1. Remove intake manifold change-over solenoid valve.
2. Disconnect connector from relevant solenoid valve for intake manifold change-over.
3. Connect one of contacts on solenoid valve to engine Ground using test leads and alligator clamp from VAG 1594.
4. Connect second contact of solenoid valve with remote control VAG 1348/3A, adapter lead VAG 1348/3-2 and auxiliary cable.
5. Operate remote control VAG 1348/3A.
6. Blow into connection to check whether solenoid valve opens correctly.

If the solenoid valve does not open

1. Replace intake manifold change-over solenoid valve.

If none of the checks already performed indicate a malfunction.

1. Re-install intake manifold change-over solenoid valve.
2. Check vacuum system for leaks.

1. Disconnect vacuum hoses from vacuum unit for intake manifold change-over system.
2. Connect hand vacuum pump VAG 1390 to vacuum unit.
3. Operate hand pump and check whether change-over function is working.
4. Check vacuum unit for leaks. (Vacuum unit should not return to rest position until hand pump is vented to atmosphere.)

If vacuum unit retracts

1. If necessary, replace vacuum unit.

If the vacuum unit is leak-free

1. Check all vacuum hoses for leaks.

In all S6 models a flap is switched in the air filter via the intake air switch-over valve -N335

Only perform test when there is a lack in performance or a DTC was registered.

The change-over on a shorter intake path in the air filter is dependent on speed and load.

Location of intake air switch-over valve -N335-. See INTAKE MANIFOLD CHANGE-OVER VALVE -N156- AND INTAKE AIR SWITCH-OVER VALVE -N335-, VACUUM DIAGRAM .

Note. At the front of the air filter lower housing there is a round opening. When reaching inside with one finger a flap can be felt.

Scheme 478

1. Start engine.
2. Accelerate sharply Flap in lower part of air filter must open at same time.

If the flap does not open when accelerating sharply

1. Check intake air switch-over valve -N335-.
2. Check vacuum system for leaks. See «VACUUM SYSTEM, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

Checking intake air switch-over valve -N335

1. Switch ignition on.
2. Perform output Diagnostic Test Mode (DTM) and actuate intake air switch-over valve -N335-. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 479

Valve should click (clicking can be heard and felt). After 1 minute output DTM is terminated.

If the solenoid valve does not click

1. Switch ignition off.
2. Unplug connector from intake air switch-over valve -N335-.
3. Measure resistance between contacts on solenoid valve using hand-held multimeter VAG 1526. Specified value: 25...35 Ohms

If the specified value is not attained

1. Replace intake air switch-over valve -N335-.

If the specified value is attained

1. Check voltage supply.

Checking voltage supply to intake air switch-over valve -N335

1. Connect diode test lamp VAG 1527 between engine Ground and socket 1 (positive) on connector using cables from adapter set VAG 1594.
2. Operate starter briefly. Diode test lamp should illuminate.

If diode test lamp does not illuminate

1. Check fuse for intake air switch-over valve -N335-. See appropriate System Wiring Diagram article.

If the fuse is OK

1. Check for open circuit and short in wiring between fuel pump relay and socket 1 on connector via fuse for intake air switch-over valve -N335-. See appropriate System Wiring Diagram article.

If the voltage supply is okay

1. Check actuation of intake air switch-over valve -N335-.
2. Re-insert fuel pump relay and fuse.

Checking actuation of intake air change-over valve -N335

1. Connect diode test lamp VAG 1527 between sockets 1 and 2 on connector for intake air switch -over valve -N335- using cables from adapter set VAG 1594.
2. Perform output Diagnostic Test Mode (DTM) and actuate intake air switch-over valve -N335-. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 480

If the diode test lamp does not flash or is continuously lit

1. Check wiring.

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .

Check the following wiring connections for open circuit and short circuit to positive or Ground.

INTAKE AIR SWITCH-OVER VALVE CIRCUIT TEST: OPENS/SHORTS (S6)

Wire resistance: max. 1.5 Ohm

See appropriate System Wiring Diagram article.

1. If wiring is OK replace engine control module. See «CONNECTING TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__connecting-test-box-vag-159831) .
2. Check intake manifold switch-over valve again for function. See «INTAKE AIR SWITCH-OVER VALVE -N335»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .
3. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

1. Remove intake air switch-over valve -N335-.
2. Disconnect connector from intake air switch-over valve.
3. Connect one contact of valve to engine Ground using test leads and alligator clamp from VAG 1594.
4. Connect second contact of valve with remote control VAG 1348/3A, adapter lead VAG 1348/3-2 and auxiliary cable to positive.
5. Operate remote control VAG 1348/3A.
6. Blow into connection to check whether solenoid valve opens correctly.

If the solenoid valve does not open

1. Replace intake air switch-over valve -N335-.

If none of the checks already performed indicate any malfunction

1. Re-install intake air switch-over valve -N335-.
2. Check vacuum system for leaks. See «CHECKING VACUUM SYSTEM OF INTAKE AIR SWITCH-OVER VALVE -N335- FOR LEAKS»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-vacuum-system-of-intake-air) .

Checking vacuum system of intake air switch-over valve -N335- for leaks

Refer to vacuum plan. See INTAKE MANIFOLD CHANGE-OVER VALVE -N156- AND INTAKE AIR SWITCH-OVER VALVE -N335-, VACUUM DIAGRAM .

1. Disconnect connector from intake air switch-over valve -N335-.
2. Connect hand pump VAG 1390 to vacuum line of flap in air filter.
3. Operate hand pump and check whether switch-over function is working.

Flap in air filter must not return to starting position as long as vacuum hand pump is not vented.

Scheme 481

If the flap goes back before the vacuum hand pump is vented

1. Check vacuum hoses for leaks.

VACUUM HOSE DIAGRAM(S)

Note. The following list refers to see scheme 141.

1. Intake Manifold Change-Over valve -N156- Actuation for both vacuum units at intake pipe
2. Intake Air Switch-over valve -N335- Actuation for flap in air filter - T-piece For vacuum supply of -N156- - Vacuum pressure supply from intake pipe - Vacuum pressure hose to flap in air filter - T-piece For vacuum supply of -N156- - T-piece For vacuum supply of -N335- and vacuum reservoir - Vacuum line to vacuum reservoir

Scheme 482

Testing for leaks

When there is no electrical supply, valve remains closed.

1. Disconnect hoses from Evaporative Emission (EVAP) canister purge regulator valve -N80-.
2. Connect auxiliary hose to one connection of valve -N80-.
3. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control unit with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.
4. Start output Diagnostic Test Mode (DTM) and select EVAP canister purge regulator valve -N80-. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 483

Solenoid valve must click...

... and should open and close (check by blowing into auxiliary hose).

If the valve does not click

1. Electrically check EVAP canister purge regulator valve. See «ELECTRICAL CHECK FOR EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR VALVE -N80»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__electrical-check-for-evaporative-emission-evap) .

If the valve does not open and close correctly

1. Replace EVAP canister purge regulator valve -N80-.

Electrical check for Evaporative Emission (EVAP) canister purge regulator valve -N80

1. Disconnect hose from Evaporative Emission (EVAP) canister purge regulator valve -N80-.
2. Measure resistance between contacts on valve using hand-held multimeter VAG 1526. Specified value: 22...30 Ohms

If specification is not attained

1. Replace Evaporative Emission (EVAP) canister purge regulator valve -N80-.

If specified value is attained

1. Check voltage supply. See «CHECKING SOLENOID VALVE VOLTAGE SUPPLY»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-solenoid-valve-voltage-supply) .

Checking solenoid valve voltage supply

Note. The EVAP canister purge regulator valve receives its power supply via the fuel pump relay.

1. Check fuse for EVAP canister purge regulator valve. See appropriate System Wiring Diagram article.

If the fuse is OK

1. Disconnect hose from Evaporative Emission (EVAP) canister purge regulator valve -N80-.
2. Connect diode test lamp VAG 1527 between engine Ground and socket 1 on connector.
3. Operate starter. Diode test lamp should illuminate.

If the diode test lamp does not illuminate

1. Check wiring from socket 1 via fuse to fuel pump relay for continuity, repair, if necessary. See appropriate System Wiring Diagram article.
2. If wiring is OK, test fuel pump relay. See «FUEL PUMP (FP) RELAY -J17- AND RELAY ACTUATION, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__fuel-pump-fp-relay-j17-and) .
3. If diode test lamp illuminates check actuation. See «CHECKING EVAP CANISTER PURGE REGULATOR VALVE ACTUATION»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-evap-canister-purge-regulator-valve) .

Checking EVAP canister purge regulator valve actuation

1. Connect the VAG 1527 diode test lamp between socket 1 (positive) and socket 2 in connector.
2. Start output DTM and select Evaporative Emission (EVAP) canister purge regulator valve -N80-. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) . Diode test lamp should flash.
3. If diode test lamp does not light or is continuously illuminated, check wiring connection.

1. Connect test box VAG 1598/31 to wiring harness for engine control control; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .

If the diode test lamp is continuously illuminated

1. Check following wiring for short to Ground.

EVAP CANISTER PURGE REGULATOR VALVE -N80- CIRCUIT TEST: SHORT TO GROUND

If the diode test lamp does not flash

1. Check for open circuit and short to positive or open circuit in following wiring connection. EVAP CANISTER PURGE REGULATOR VALVE -N80- CIRCUIT TEST: SHORT TO POSITIVE OR OPEN 2-pin connector on wiring harness, socket Test box VAG 1598/31 socket 2 64 Wire resistance: max. 1.5 Ohm
2. If necessary, correct short circuit to Ground or open circuit. See appropriate System Wiring Diagram article.

If no short or open circuit is found

1. Replace engine control module -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .

Secondary Air Injection (AIR) solenoid valve -N112-, checking

Location of secondary air injection solenoid valve. See COMPONENT LOCATIONS OVERVIEW .

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control unit with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.
2. Start Output Diagnostic Test Mode (DTM) and activate secondary air injection solenoid valve. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 484

Secondary air injection solenoid valve must click.

If the secondary air injection solenoid valve does not click

1. Disconnect 2-pin connector from solenoid valve.
2. Connect diode test lamp VAG 1527 to disconnected connector using test leads from VAG 1594.
3. Repeat Output DTM.

If the diode test lamp now flashes during the DTM

1. Replace secondary air injection solenoid valve.

If the diode test lamp still does not flash

1. Switch ignition off.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Check for open circuit in following wiring connections: SECONDARY AIR INJECTION SOLENOID VALVE CIRCUIT TEST: OPENS 2-pin connector on wiring harness, socket Test box VAG 1598/31 socket 2 44 Wire resistance: max. 1.5 Ohm

If no wiring malfunction is detected

1. Check voltage supply for secondary air injection system according to wiring diagram: See appropriate System Wiring Diagram article.
2. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Secondary Air Injection (AIR) pump relay -J299-, checking

Note. The secondary air injection pump relay is located in the triple relay carrier in the electronics box in the plenum chamber (position 2.

Scheme 485

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control unit with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.
2. Start Output Diagnostic Test Mode (DTM) and activate secondary air injection pump relay. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 486

Secondary Air Injection (AIR) pump relay -J299- actuates secondary air injection (AIR) pump motor -V101-. This runs in intervals.

If Secondary air injection (AIR) pump motor -V101- does not run in intervals

1. Disconnect 2-pin connector from secondary air injection pump motor and connect diode test lamp VAG 1527 to disconnected connector using auxiliary cables from VAG 1594.
2. Repeat Output DTM.

If the diode test lamp now flashes during the DTM

1. Replace Secondary air injection pump motor -V101-: See «EXHAUST SYSTEM COMPONENTS, REMOVING AND INSTALLING»(/audi/s6/c5-1999-2004/remont/exhaust/#exhaust-system-42l-v8-5v-art-awn-bbd__exhaust-system-components-removing-and-installing) .

If the diode lamp does not flash and the secondary air injection pump relay does not click, check actuation of secondary air injection pump relay. See CHECKING ACTUATION OF SECONDARY AIR INJECTION PUMP RELAY .

If the diode lamp does not flash but the secondary air injection pump relay clicks, check voltage supply of secondary air injection pump relay

Checking voltage supply of secondary air injection pump relay

1. Check fuse for secondary air injection pump relay -J299-. See appropriate System Wiring Diagram article.

If the fuse is not faulty

1. Remove secondary air injection pump relay from relay carrier. See appropriate System Wiring Diagram article.
2. Check voltage supply (positive 30) for relay. See appropriate System Wiring Diagram article.
3. If no malfunctions are found in voltage supply for relay replace Secondary air injection (AIR) pump relay -J299-.

Checking actuation of secondary air injection pump relay

1. Switch ignition off.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Remove secondary air injection pump relay from relay carrier. See appropriate System Wiring Diagram article.
4. Check for open circuit in following wiring connections: SECONDARY AIR INJECTION PUMP RELAY CIRCUIT TEST: OPENS Test box VAG 1598/31 socket Secondary air injection pump relay, contact 46 6 See appropriate System Wiring Diagram article. Wire resistance: max. 1.5 Ohm

If no wiring malfunction is detected

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__motronic-engine-control-module-ecm-j220) .
2. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Function of the electronic throttle system

In the electronic throttle system, the throttle valve is not operated by a cable connected to the accelerator pedal. There is no mechanical connection between the accelerator pedal and the throttle valve.

The position of the accelerator pedal is communicated to the engine control module by two accelerator position sensors (variable resistances located in a single housing) connected to the accelerator pedal.

The position of the accelerator pedal (determined by the driver) is one of the main input parameters to the engine control module.

The throttle valve is actuated over the full range of engine speed and power by an electric motor (throttle drive) in the throttle valve control module.

The throttle drive moves the throttle valve as instructed by the engine control module.

When the engine is running (and under load), the engine control module can open and close the throttle valve independently of the accelerator position sensors.

It would be incorrect to assume that EPC consists of just one or two components. EPC is better described as a system which contains all components necessary to determine the throttle valve position and for controlling and monitoring this position. These components include, for example, the throttle valve control module, the EPC warning lamp, and the engine control module.

The following components are located in the housing of the throttle valve control module

(This housing must not be opened)

1. Throttle drive (power accelerator actuation) -G186- (This is an electric motor which is activated by the engine control module. The electric motor opens the throttle valve against the force of a spring).
2. Angle sensor -1- for throttle drive (power accelerator actuation) -G187
3. Angle sensor -2- for throttle drive (power accelerator actuation) -G188

Note. The angle sensors are in the form of potentiometers (variable resistances). They provide the position of the throttle valve to the engine control module completely independently of one another (redundant system). The potentiometers cannot be adjusted mechanically. The settings are made as part of basic setting (function 04) using the vehicle diagnostic, testing and information system VAS 5051 or the V.A.G 1551 Scan Tool.

Throttle valve control module, adaptation

The adaptation process enables the engine control module to learn the various positions of the throttle valve with the ignition switched on and the engine not running. These positions are stored in the control module. The feedback signal indicating the position of the throttle valve comes from the two throttle valve drive angle sensors.

An adaptation must always be performed if the throttle valve control module -J338- or the engine control module is removed and reinstalled or replaced, or if the voltage supply to the engine control module is interrupted.

The learning process (adaptation process) is performed

1. By initiating the basic setting (Function 04) of display group 60 with ignition switched on.
2. Automatically if the ignition is switched on once for at least 6 seconds without actuating the starter or the accelerator pedal and the engine control module recognizes "adaptation requirement". In this case, however, it is not obvious whether the adaptation process was successful or not. Adaptation requirement is recognized if stored voltage values from the angle sensors do not coincide with current measured voltage values in a certain tolerance band.

Test conditions for adaptation of the throttle valve control module

1. No DTC stored in DTC memory. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__diagnostic-trouble-code-dtc-memory-checking) .
2. Engine stopped, ignition switched on
3. Accelerator not depressed
4. Coolant temperature greater than 5 °C but less than 105 °C
5. Intake air temperature above 5 °C
6. Voltage supply to engine control module greater than 11 V, testing. See «CONTROL MODULE POWER SUPPLY, CHECKING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control unit with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 487

1. Press keys 0 and 4 for function "Introduction of basic setting" and confirm entry with Q key.

Indicated on display

Scheme 488

1. Press keys 0, 6 and 0 for "display group number 60" and confirm entry with Q key.

Indicated on display

Scheme 489

After the Q key is pressed, the throttle drive is first disconnected from the electrical supply.

In this condition, the throttle valve is pulled into an emergency running position by a mechanical spring which is located in the throttle valve control module. The values supplied by the two angle sensors in this emergency running position are stored in the engine control module.

The throttle valve is then opened by a predetermined amount. When this value is reached, the throttle drive is again disconnected from the electrical supply. The mechanical spring should then close the throttle valve to the previously adapted emergency running position within a specified period of time (spring test).

The throttle drive then closes the throttle valve; the values supplied by the angle sensors in the throttle valve control module are stored in the engine control module.

If the engine control module disconnects the throttle drive from the electrical supply while the vehicle is being driven, the result will be an increased and fluctuating idling speed and a very poor throttle response.

1. Check specified value for throttle valve control module (display zones 3 and 4). DISPLAY GROUP 60: ADAPTATION OF THROTTLE VALVE CONTROL MODULE WITH IGNITION ON Display zones 1 2 3 4 Display group 60: Adaptation of throttle valve control module with ignition on Display xxx% xxx% --- --- Display Throttle angle (angle sensor 1) Throttle angle (angle sensor 2) Adaptation stage counter Adaptation status Range min.: 0% max.: 100% min.: 0% max.: 100% 0 to 8 ADP process running ADP process OK ERROR Specified value xxx% xxx% During the adaptation process, the adaptation stage counter should run up from 0 to 8. (Some of the numbers may not appear) . ADP process running Note: If specified value is not attained: Notes . See «Notes»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__notes) .
2. Check specified value for throttle valve control module (display zones 3 and 4).

DISPLAY GROUP 60: ADAPTATION OF THROTTLE VALVE CONTROL MODULE WITH IGNITION ON

Notes

Note. If the adaptation process is interrupted by the control module and the tester display indicates "Function is unknown or cannot be carried out at the moment" the cause could be one of the following.

1. All test conditions may not have been met. See «TEST CONDITIONS FOR ADAPTATION OF THE THROTTLE VALVE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__test-conditions-for-adaptation-of-the) .
2. Engine was started or accelerator was actuated during the adaptation process
3. The throttle valve cannot close completely (e.g. dirt)
4. Connector (6-pin connector) at throttle valve control module not engaged
5. Wiring connections faulty
6. Distortion of throttle valve housing (check screw connection)
7. The throttle valve control module is faulty

1. End engine basic setting by pressing --> key.
2. Press keys 0 and 6 for function "End data transfer" and confirm entry with Q key.

Angle sensor -1- for throttle drive (power accelerator actuation) -G187- and Angle sensor -2- for throttle drive (power accelerator actuation) -G188-, checking

The throttle valve drive angle sensors -G187- and -G188- signal the position of the throttle valve to the engine control module. Both angle sensors are located in the throttle valve control module.

If a DTC relating to angle sensors for throttle valve drive -G187- or -G188- is stored in the DTC memory, check voltage supply to the throttle valve control module.

Checking the voltage supply to the throttle valve control module

1. Check fuse for throttle valve control module. See appropriate System Wiring Diagram article.

If the fuse is OK

1. Disconnect connector from throttle valve control module.
2. Switch ignition on.
3. Connect hand-held multimeter between following sockets on connector to measure voltage

THROTTLE VALVE CONTROL MODULE CIRCUIT TEST: VOLTAGE SUPPLY

If the specified values are not attained, test wiring between the engine control unit to the throttle valve control parts. See CHECKING WIRING FOR VOLTAGE, SIGNAL AND ACTUATION .

If specifications are attained, also check the signal and activation wiring of the throttle drive actuation. See CHECKING WIRING FOR VOLTAGE, SIGNAL AND ACTUATION .

Checking wiring for voltage, signal and actuation

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check following wiring connections for open circuit and short circuit to positive or Ground. THROTTLE VALVE CONTROL MODULE CIRCUIT TEST: OPENS/SHORTS 6-pin connector on wiring harness, socket Test box VAG 1598/31, socket 1 92 2 83 3 117 4 84 5 118 6 91 Wire resistance: max. 1.5 Ohm
3. Correct any open/short circuits as necessary. See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace throttle valve control module.
2. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Throttle Position (TP) sensor -G79- and Sender 2 for accelerator pedal position -G185-, checking

Both the Throttle Position (TP) sensors -G79- and the Sender 2 for accelerator position -G185- are located on the accelerator pedal and independently signal the driver's requirements to the engine control module. Both are located in one housing.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 490

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 491

1. Press keys 0, 6 and 2 for "display group number 62" and confirm entry with Q key.

Note. The engine control module converts and displays the voltage readings from the angle sensors as percentages of 5 V. (5 Volt supply corresponds to 100%).

Indicated on display

Scheme 492

1. Check specifications for electronic throttle potentiometer voltages. DISPLAY GROUP 62: ELECTRONIC THROTTLE POTENTIOMETER VOLTAGES WITH IGNITION ON Display zones 1 2 3 4 Display group 62: Electronic throttle potentiometer voltages with ignition on Display xx% xx% xx% xx% Display Throttle valve angle (angle sensor 1) Throttle valve angle (angle sensor 2) Sender 1 for accelerator pedal position Sender 2 for accelerator pedal position Range min.: 0% max.: 100% min.: 0% max.: 100% min.: 0% max.: 100% min.: 0% max.: 100% Specified value 3...93% 97...3% 12...92% 4...49%
2. Observe readouts in display zones 3 and 4.
3. Slowly depress accelerator pedal.

Percentage displayed in zone 3 should rise evenly. Tolerance range from 12...92% is not fully utilized.

Percentage displayed in zone 4 should also rise evenly. Tolerance range from 4...49% is not fully utilized.

Note. The value displayed in zone 3 must always be about twice as large as that in zone 4.

If the displays are not as described

1. Check voltage supply and wiring for TP sensor/Sender 2 for accelerator pedal position. See «CHECKING VOLTAGE SUPPLY FOR TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-voltage-supply-for-tp-sensorsender) .
2. Adjust TP sensor/Sender 2 for accelerator pedal position. See «ACCELERATOR PEDAL CABLE, ADJUSTING»(/audi/s6/c5-1999-2004/remont/fuel-system/#fuel-supply-system-all-engines__accelerator-pedal-cable-adjusting) .

Checking voltage supply for TP sensor/Sender 2 for accelerator pedal position

1. Remove driver's storage compartment/trim. See «DRIVER'S STORAGE COMPARTMENT, REMOVING»(/audi/s6/c5-1999-2004/remont/mirrors/#interior-equipment__drivers-storage-compartment-removing) .
2. Disconnect connector for TP sensor/Sender 2 for accelerator pedal position.

Note. The connector is clipped onto the pedal bracket near the brake light switch.

1. Switch ignition on.
2. Connect hand-held multimeter (voltage range) between following sockets on connector

Vehicles up to model year 2001

TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION CIRCUIT TEST: VOLTAGE SUPPLY, VEHICLES UP TO MODEL YEAR 2001

Vehicles from model year 2002

TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION CIRCUIT TEST: VOLTAGE SUPPLY, VEHICLES FROM MODEL YEAR 2002

If specifications are attained

1. Additionally check signal wires. See «CHECKING SIGNAL WIRING AND WIRING CONNECTIONS BETWEEN TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION AND ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-signal-wiring-and-wiring-connections) .

If the specified values are not obtained

1. Check wiring between engine control module and TP sensor/Sender 2 for accelerator pedal position. See «CHECKING SIGNAL WIRING AND WIRING CONNECTIONS BETWEEN TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION AND ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__checking-signal-wiring-and-wiring-connections) .

Checking signal wiring and wiring connections between TP sensor/Sender 2 for accelerator pedal position and engine control module

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check for open circuit and short to positive or Ground in following wiring connections

Vehicles up to model year 2001

TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION CIRCUIT TEST: OPENS/SHORTS, VEHICLES UP TO MODEL YEAR 2001

Vehicles from model year 2002

TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION CIRCUIT TEST: OPENS/SHORTS, VEHICLES FROM MODEL YEAR 2002

Wire resistance: max. 1.5 Ohm

1. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no wiring malfunction is detected

1. Replace TP sensor/Sender 2 for accelerator pedal position. See «ACCELERATOR PEDAL (AP) WITH POSITION SENSORS, REMOVING AND INSTALLING»(/audi/s6/c5-1999-2004/remont/fuel-system/#fuel-supply-system-all-engines) .

Kick down switch point, checking

After replacing the engine control module and after replacement of the accelerator pedal, the kick down switch in vehicles with automatic transmission must be subjected to adaptation.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 493

1. Press keys 0 and 4 for function "Basic Setting" and confirm entry by pressing Q key.

Indicated on display

Scheme 494

1. Press keys 0, 6 and 3 for "display group number 63" and confirm entry with Q key.

Indicated on display

Scheme 495

1. Observe readout in display zone 4. DISPLAY GROUP 63: ADAPTATION OF KICK DOWN SWITCH WITH IGNITION ON Display zones 1 2 3 4 Display group 63: Adaptation of kick down switch with ignition on Display xx% xx% Kickdown Starting Display Potentiometer 1 for pedal value sender Potentiometer 2 for pedal value sender Switch Adaptation Range min.: 0% max.: 100% min.: 0% max.: 100% Kickdown Starting ADP. running ADP. OK ADP ERROR Specified value 10...20% 4...10% Kickdown Starting Note
2. Push accelerator pedal via kick down pressure point until limit stop.
3. Hold accelerator pedal for at least 2 seconds at limit stop.

DISPLAY GROUP 63: ADAPTATION OF KICK DOWN SWITCH WITH IGNITION ON

Brake light switch -F- and Brake pedal switch -F47-, checking

Because the injection system operates with an accelerator pedal sensor (potentiometer) which may be faulty, the engine is regulated for reasons of safety when the brakes are operated. For this purpose, the control module requires signals from both the brake light switch and the brake pedal switch.

This means that if the brakes are operated when the accelerator pedal is held at a constant position, the engine speed is immediately reduced. Incorrectly adjusted switches may lead to undesired control action.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 496

1. Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 497

1. Press keys 0, 6 and 6 for "display group number 66" and confirm entry with Q key.

Indicated on display

Scheme 498

1. Observe readout in display zone 2. DISPLAY GROUP 66: SIGNALS TO ENGINE CONTROL MODULE WITH IGNITION ON Display zones 1 2 3 4 Display group 66: Signals to engine control module with ignition on Display xxx km/h 1 0 0 0 xxx km/h 1 0 0 0 Display ACTUAL speed Switch settings SPECIFIED speed Switch positions for cruise control system Range off = 0 on = 1 off = 0 on = 1 Specified value 1 0 0 0 Note: Relevance of figures . See «Meaning of 4 digit readout of display zone 2»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__meaning-of-4-digit-readout-of)
2. Depress brake pedal.

Meaning of 4 digit readout of display zone 2

MEANING OF 4 DIGIT READOUT OF DISPLAY ZONE 2

DISPLAY GROUP 66: SIGNALS TO ENGINE CONTROL UNIT

1. Allow brake pedal to return slowly to its normal position. Both displays should change from 1 back to 0.

If one or both displays do not change

1. Check voltage supply. See «CHECKING WIRING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

1. Remove driver's storage compartment/trim. See «DRIVER'S STORAGE COMPARTMENT, REMOVING»(/audi/s6/c5-1999-2004/remont/mirrors/#interior-equipment__drivers-storage-compartment-removing) .
2. Disconnect 4-pin connector on brake pedal.
3. Connect hand-held multimeter (voltage range) between following sockets on the connector
4. Switch ignition off. BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH CIRCUIT TEST: IGNITION OFF 4-pin connector on wiring harness, socket Specified value 1 + Ground Battery voltage
5. Switch ignition on.

BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH CIRCUIT TEST: IGNITION ON

If the specified values are attained

1. Check wiring. See «CHECKING WIRING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

If the specified values are not attained

1. Check wiring connections from sockets 1 and 3 of connector for open circuit/short to Ground. See appropriate System Wiring Diagram article.
2. Correct any open/short circuit as necessary.

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check following wiring connections for open circuit and short circuit to positive or Ground. BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH CIRCUIT TEST: OPENS/SHORTS 4-pin connector on wiring harness, socket Test box VAG 1598/31, socket 2 56 4 55 Wire resistance: max. 1.5 Ohm
3. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no open circuit is detected

1. Replace brake light/brake pedal switch.

Clutch vacuum vent valve switch -F36-, checking

This signal is designed to prevent speed overshoots and jerkiness on switching from throttle open to throttle closed and vice versa when disengaging the clutch. It is needed for the cruise control system.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control unit with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 499

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 500

1. Press keys 0, 6 and 6 for "display group number 66" and confirm entry with Q key.

Indicated on display

Scheme 501

1. Observe readout in display zone 2. DISPLAY GROUP 66: SIGNALS TO ENGINE CONTROL MODULE Display zones 1 2 3 4 Display group 66: Signals to engine control module Display xxx km/h 0 0 0 0 xxx km/h 0 0 0 0 Display ACTUAL speed Switch settings SPECIFIED speed Switch positions for cruise control system Range off = 0 on = 1 off = 0 on = 1 Specified value 0 0 0 0 Note: Relevance of figures . See «Meaning of 4 digit readout of display zone 2»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd)
2. Depress clutch pedal

MEANING OF 4 DIGIT READOUT OF DISPLAY ZONE 2

DISPLAY GROUP 66: SIGNALS TO ENGINE CONTROL MODULE

1. Allow clutch pedal to return slowly to its normal position. Display should change from 1 back to 0.

If display does not change

1. Check power supply. See «CHECKING POWER SUPPLY»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

1. Remove driver's storage compartment/trim. See «DRIVER'S STORAGE COMPARTMENT, REMOVING»(/audi/s6/c5-1999-2004/remont/mirrors/#interior-equipment__drivers-storage-compartment-removing) .
2. Disconnect 2-pin connector from clutch pedal.
3. Switch ignition on.
4. Connect hand-held multimeter (voltage range) between following sockets on connector

CLUTCH VACUUM VENT VALVE SWITCH CIRCUIT SUPPLY: POWER SUPPLY

If specified value is attained

1. Check wiring. See «CHECKING WIRING»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd) .

If specified value is not attained

1. Check wiring connections from socket 2 of connector for open circuit/short to Ground. See appropriate System Wiring Diagram article.

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check following wiring connections for open circuit and short to positive or Ground. CLUTCH VACUUM VENT VALVE SWITCH CIRCUIT SUPPLY: OPENS/SHORTS 2-pin connector on wiring harness, socket Test box VAG 1598/31, socket 1 39 Wire resistance: max. 1.5 Ohm
3. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no open circuit is detected

1. Replace clutch vacuum vent valve switch.

Crash signal, checking

In the event of an accident (crash) which results in the triggering of the belt tensioner/airbag, the engine control module deactivates the fuel pump relay. Excessive escape of fuel in the event of damage to the fuel system is thus prevented.

As long as the code "Crash deactivation triggered" is stored in the engine control module or is not erased, the fuel pump supply is blocked at "ignition ON" (no generation of preliminary pressure in the fuel system). This can result in a delay when starting the engine.

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check following wiring connections for open circuit and short circuit to positive or Ground. CRASH SIGNAL CIRCUIT CHECK: OPENS/SHORTS Test box VAG 1598/31 Socket Airbag control module Contact 67 See appropriate System Wiring Diagram article. Wire resistance: max. 1.5 Ohm
3. Correct any open/short circuit as necessary.

If no wiring malfunction is detected

1. Check DTC memory of airbag control module
2. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Engine speed signal, checking

Note. The signal is generated by the Engine speed (RPM) sensor -G28- and processed by the engine control module.

Determine the engine speed, as follows

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, ignition must be switched on.

Indicated on display

Scheme 502

1. Check all control modules for a missing engine speed signal via "Automatic test sequence".
2. Press "0" key twice for "automatic test sequence" function and confirm entry with Q key. No DTCs relating to a "missing engine speed signal" should be stored in any of control modules.

If one of the control modules indicates a malfunction

1. Locate open circuit or short circuit between engine control module and control module concerned. See appropriate System Wiring Diagram article.

Air conditioner compressor shut-off, checking

Note. The air conditioning compressor signal informs the engine control module that the compressor will be switched on in 140 ms. The engine control module can send a signal via the same wire to shut off the air conditioner compressor. Switching off of the air conditioner compressor occurs: In the emergency program (Emergency running mode) After initiating of basic setting (Function 04) From the transmission control module (Kick down function)

1. Air conditioner functioning properly.
2. No DTCs recorded in DTC memory of engine control module
3. Interior temperature of more than +15 °C

1. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 503

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 504

1. Press keys 0, 5 and 0 for "display group number 50" and confirm entry with Q key.

Indicated on display

Scheme 505

1. Check compressor shut-off in display zone 4. DISPLAY GROUP 50: SIGNALS TO ENGINE CONTROL MODULE Display zones 1 2 3 4 Display group 50: Signals to engine control module Display xxx rpm xxx rpm A/C low Compr. OFF Display Actual engine speed (actual value) Specified engine speed (theoretical value) Air conditioner requirement Air conditioner compressor operating status Range A/C - low A/C - high Compr. OFF Compr. ON Specified value A/C - low Compr. OFF Note
2. Switch on air conditioner by pressing "Auto" key. Compressor should run (display zone 4).
3. Set air conditioner to maximum cooling or heating output (display zone 3). DISPLAY GROUP 50: SIGNALS TO ENGINE CONTROL MODULE Display zones 1 2 3 4 Display group 50: Signals to engine control module Display xxx rpm xxx rpm A/C - high Compr. ON Display Actual engine speed (actual value) Specified engine speed (theoretical value) Air conditioner requirement Air conditioner compressor operating status Range A/C - low A/C - high Compr. OFF Compr. ON Specified value A/C - high Compr. ON Note
4. Switch off air conditioning compressor at A/C control head by pressing ECON button. Specification for display zone 4: Display should change from "Compr. ON" to "Compr. OFF" (compressor switch-off)

If the readout in display zone 4 is not as described

1. Switch ignition off.
2. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
3. Check following wiring connections for short circuit to positive or Ground or open circuit. AIR CONDITIONER COMPRESSOR SHUT-OFF CIRCUIT TEST: OPENS/SHORTS Test box VAG 1598/31 Socket A/C Control head -E87- Contact 41 See appropriate System Wiring Diagram article. Wire resistance: max. 1.5 Ohm
4. Correct any open/short circuit as necessary.
5. If there are no wiring malfunctions, check operation of air conditioning. See «A/C SYSTEM, ON BOARD DIAGNOSTIC (OBD)»(/audi/s6/c5-1999-2004/remont/heated-glassdefoggers/#on-board-diagnostic-obd-hvac__ac-system-on-board-diagnostic-obd) .
6. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Engine mountings, checking

Hydraulically dampened engine mountings with electric actuation prevent oscillations of the engine being transferred to the body throughout the entire speed range.

In idling operation the engine mountings are soft.

In driving operation the engine mountings are hard.

1. Switch ignition on.
2. Perform Output Diagnostic Test Mode (DTM) and actuate engine mounting. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) .

Indicated on display

Scheme 506

1. Press -> key.

Indicated on display

Scheme 507

Upon actuation of engine mounting, both solenoid valves should give a clearly audible click.

If specified value is not attained, perform the following tests

Checking voltage supply of engine mountings

1. Disconnect connector from relevant solenoid valve.
2. Connect diode test lamp VAG 1527 between engine Ground and socket 1 (positive) on connector using cables from adapter set VAG 1594.
3. Operate starter for a few seconds. Engine may start. Diode test lamp should illuminate.

If the diode test lamp does not illuminate, perform the following tests

1. Checking fuse for engine mounting. See appropriate System Wiring Diagram article.

If the fuse is OK

Scheme 508

1. Check wiring from socket 1 via fuse to fuel pump relay for continuity. See appropriate System Wiring Diagram article.

Checking actuation of engine mountings

1. Disconnect connector from relevant engine mounting.
2. Connect diode test lamp VAG 1527 between sockets 1 (positive) and 2 on connector of relevant solenoid valve using cables from adapter set VAG 1594.
3. Actuate output DTM and actuate relevant engine mounting. See «OUTPUT DIAGNOSTIC TEST MODE (DTM)»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__output-diagnostic-test-mode-dtm) . Diode test lamp should flash upon actuation of engine mounting.

If the diode test lamp is continuously lit

1. Check wiring connections from socket 2 of relevant connector for engine mounting for Ground short.

If the diode test lamp does not flash

1. Check wiring connection.

Scheme 509

1. Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .
2. Check wiring connection of relevant engine mounting connector for open circuits as well as shorts to positive. ENGINE MOUNTINGS CIRCUIT TEST: OPENS/SHORTS 2-pin connector on wiring harness, contact Test box VAG 1598/31, socket Left Electro-Hydraulic Engine Mount Solenoid Valve -N144- 2 105 Right Electro-Hydraulic Engine Mount Solenoid Valve -N145- 2 116 Wire resistance: max. 1.5 Ohm
3. Correct any open/short circuit as necessary. See appropriate System Wiring Diagram article.

If no short or open circuit is found.

1. Replace relevant injector.
2. Read readiness code. Generate readiness code again if DTC memory was erased. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Consumption signal, checking

Test is valid only for vehicles up to m.y. 2000.

This signal is required for the consumption display in the instrument cluster.

If an incorrect fuel consumption is displayed in instrument cluster

1. Adapt consumption display to the actual consumption. See «ADAPTATION (SCAN TOOL FUNCTION 10)»(ref-196293-S39185717022005100900000) .

If no fuel consumption is displayed in instrument cluster

1. Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .

The following wire connections must be checked for short circuit to B+, Ground (GND) and for open circuit

CONSUMPTION SIGNAL CIRCUIT TEST: OPENS/SHORTS

Wire resistance: max: 1.5 Ohm

1. Repair open circuit or short circuit if necessary.
2. Read readiness code. If DTC memory was erased, readiness code must be re-generated. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Speed signal, checking

Test is valid only for vehicles up to m.y. 2000.

Note. The vehicle speed signal is generated by the Vehicle Speed Sensor (VSS) -G68- (at transmission) and processed in the instrument cluster. The processed signal enters at terminal 54 of the ECM and is used for idle stabilization and tip-in shock reduction during shifting.

1. Connect VAS5051 tester or VAG1551 Scan Tool and select control module for engine electronics 1 using "address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . Engine must run at idle for this.

Indicated on display

Scheme 510

1. Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.

Indicated on display

Scheme 511

1. Press buttons -0-, -0- and -5- to select "Display group number 5". Press -Q- button to confirm input.

Indicated on display

Scheme 512

1. Perform a road test.

1. Check specified value for vehicle speed.

DISPLAY GROUP 5: VEHICLE SPEED

If the vehicle speed is not indicated.

1. Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .

The following wire connections must be checked for short circuit to B+, short circuit to Ground (GND) and for open circuit

SPEED SIGNAL CIRCUIT TEST: OPENS/SHORTS

Wire resistance: max: 1.5 Ohm

1. Repair open circuit or short circuit if necessary.

If no malfunctions are found in wiring

1. Determine all "users" of speed signal (e.g. radio, automatic transmission, A/C system, etc.), disconnect those with a connection to instrument cluster one after another and repeat test until cause is detected.
2. Read readiness code. If DTC memory was erased, readiness code must be re-generated. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Fuel level signal, checking

Test is valid only for vehicles up to m.y. 2000.

If the "fueling pump" symbol lights up in instrument cluster (customer requested to fill up), fuel level signal is sent to Engine Control Module (ECM). Fuel level signal and left heated door lock control module -G210- are evaluated in Engine Control Module (ECM) in order to be able to shut off engine running with empty tank.

1. Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM. See «WIRING AND COMPONENT CHECK WITH TEST BOX VAG 159831»(/audi/s6/c5-1999-2004/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-5v-bbd__wiring-and-component-check-with-test) .

The following wire connections must be checked for short circuit to B+, short circuit to Ground (GND) and for open circuit

FUEL LEVEL SIGNAL CIRCUIT TEST: OPENS/SHORTS

Wire resistance: max: 1.5 Ohm

1. Repair open circuit or short circuit if necessary.
2. Read readiness code. If DTC memory was erased, readiness code must be re-generated. See «READINESS CODE, GENERATING»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) .

Exchange of data between connected control modules, checking

Note. Data is exchanged between individual control modules by means of a bus system. "CAN bus" is used to describe a system that transports and distributes data. The wires between the control modules that are used to transfer the data are known as signal wires. Data is transmitted via data wires in sequence, i.e. in a specific order to the connected control modules (e.g. engine rpm and accelerator pedal position).

Testing the bus system

The Diagnostic Trouble Code (DTC) table includes instructions to check the data exchange between engine control module, transmission (gearbox) control module and the ABS control module and/or instrument cluster (dash insert).

1. Check that multiple connectors for control modules are properly seated.
2. Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd__vehicle-diagnostic-testing-and-information-system) or «V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE»(/audi/s6/c5-1999-2004/remont/testing-diagnostics/#on-board-diagnostic-obd-42l-v8-5v-bbd) . For this purpose, engine must be running at idle speed.

Indicated on display

Scheme 513

1. Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Scheme 514

1. Press keys 1, 2 and 5 for "display group number 125" and confirm entry with Q key.

Indicated on display

Scheme 515

DISPLAY GROUP 125: CAN BUS MESSAGES

Automatic test sequence

1. Press key 0 twice for address word "Automatic test sequence" and confirm entry with Q key. V.A.G 1551 transmits all known address words in sequence.

If a control module answers with its identification, the number of malfunctions stored or "No malfunction detected" appears on the display.

Any system DTCs stored will be displayed in sequence and printed out. The V.A.G 1551 will then transmit the next address word.

The automatic test sequence has ended when this display appears

Scheme 516

If malfunction relating to "Data bus..." or "...no message" is displayed

1. Check to make sure that vehicle is installed with correct engine control module, transmission control module, ABS control module and instrument cluster (check part numbers and code).

If the correct control modules are installed

1. Check that multiple connectors for control modules are properly seated.

When multiple connectors are tight

1. Check CAN bus system.

Checking a "two-line bus system"

The communication between three or more control modules is performed via a "two-line bus system" .

1. Evaluate malfunctions stored in control modules.

Note. This helps to localize line malfunctions.

Example 1

The malfunctions stored in the memories indicate that control module 1 does not communicate with control modules 2 and 3.

Scheme 517

CONTROL MODULE 1 DOES NOT COMMUNICATE WITH CONTROL MODULES 2 AND 3 DIAGNOSIS

1. Switch ignition off.
2. Disconnect control modules connected to each other via bus lines and investigate whether there is a short circuit between bus lines. See appropriate System Wiring Diagram article.

If no malfunction can be detected in the bus lines

1. Replace control module 1.

Example 2

The malfunctions stored in the memories indicate that the control module 2 does not communicate with control modules 1 and 3.

Scheme 518

CONTROL MODULE 2 DOES NOT COMMUNICATE WITH CONTROL MODULES 1 AND 3 DIAGNOSIS

1. Switch ignition off.
2. Disconnect control modules connected to each other via bus lines and investigate whether there is a short circuit between bus lines. See appropriate System Wiring Diagram article.

If no malfunction can be detected in the bus lines

1. Replace control module 2.

Example 3

With the malfunctions stored in the memory it can be seen that there is no sending or receiving operation possible in any of the control modules.

CONTROL MODULE MALFUNCTIONS STORED IN MEMORY

Scheme 519

1. Switch ignition off.
2. Disconnect control modules that are linked by bus wires and check for a short circuit between bus wires See appropriate System Wiring Diagram article.
3. Check bus wires for short to positive and short to Ground.

If cause of malfunction "Data bus drive faulty" cannot be found in bus lines check whether one of the control modules is responsible.

1. All the control modules that communicate via the CAN data bus are still disconnected.
2. The ignition is switched off.

1. Connect one control module.
2. Connect V.A.G 1551 Scan Tool. Switch ignition on and erase Diagnostic Trouble Code (DTC) memory of control module that has just been connected
3. Terminate DTC memory readout by selecting function 06 "End output".
4. Switch ignition off and then on again.
5. Leave ignition switched on for 10 seconds. Check DTC memory of control module that has just been connected, using Scan Tool.
6. If "Data bus drive faulty" is now indicated, replace control module which has just been connected.
7. If "Signal wire defect" is not read out, connect next control module and repeat procedure.

See also:
• MALFUNCTION INDICATOR LAMP (MIL) -K83-, FUNCTION
• ELECTRONIC POWER CONTROL (EPC) WARNING LAMP -K132- (FOR ELECTRONIC THROTTLE), FUNCTION
• VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING ENGINE CONTROL MODULE
• V.A.G 1551 SCAN TOOL, CONNECTING AND SELECTING ENGINE CONTROL MODULE
• ENGINE CONTROL MODULE (ECM), CODING
• ADAPTATION AFTER REPLACING ENGINE CONTROL MODULE
• DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING
• FUEL PUMP (FP) -G6-, CHECKING
• OUTPUT DIAGNOSTIC TEST MODE (DTM)
• FRONT EXHAUST PIPE WITH THREE WAY CATALYTIC (TWC) CONVERTER (LEFT SIDE), REMOVING AND INSTALLING
• FRONT EXHAUST PIPE WITH CATALYTIC CONVERTER, REMOVING AND INSTALLING (RIGHT SIDE)
• EXHAUST SYSTEM COMPONENTS, REMOVING AND INSTALLING
• ACCELERATOR PEDAL CABLE, ADJUSTING
• DRIVER'S STORAGE COMPARTMENT, REMOVING
• A/C SYSTEM, ON BOARD DIAGNOSTIC (OBD)
• Removing engine control module
• THROTTLE VALVE CONTROL MODULE, ADAPTATION
• Kick down switch point, checking
• REPLACING ENGINE CONTROL MODULES WHICH ARE SECURED WITH A PROTECTIVE HOUSING
• ACTIVATING CRUISE CONTROL SYSTEM
• IF THE IDLING SPEED IS TOO HIGH OR TOO LOW OR NOT SMOOTH AND THERE ARE NO DTCS RECORDED IN THE DTC MEMORY, PERFORM THE FOLLOWING TESTS MARKED WITH A DOT
• Meaning of 5 digit readout of display group 56
• CHECKING OXYGEN SENSOR LEARNED VALUES AND OXYGEN SENSOR CONTROL
• WIRING AND COMPONENT CHECK WITH TEST BOX VAG 1598/31
• CHECKING WIRING
• MOTRONIC ENGINE CONTROL MODULE (ECM) -J220-, REPLACING
• CHECKING ACTUATION OF FUEL PUMP RELAY
• CHECKING ACTUATION OF FUEL PUMP AND COMPONENTS
• CHECK THE POWER SUPPLY
• CHECKING WIRING BETWEEN POWER SUPPLY RELAY AND ENGINE CONTROL MODULE
• Evaluation of display group 4
• CHECKING VOLTAGE SUPPLY FROM TERMINAL 15 AND TERMINAL 30
• Evaluation of display group 002
• CHECKING VOLTAGE SUPPLY TO MAF SENSOR
• CHECKING GROUND CONNECTION
• CHECKING WIRING TO MAF SENSOR
• COMPONENT LOCATIONS OVERVIEW
• Meaning of 3 digit readout of display group 30
• OXYGEN SENSOR SIGNAL WIRING AND ACTUATION, CHECKING
• OXYGEN SENSOR HEATING, CHECKING
• IF SPECIFICATION IS NOT ATTAINED IN DISPLAY ZONE 1 OR DISPLAY ZONE 3, OR IF THE VALUE DOES NOT FLUCTUATE BY AT LEAST 2%
• Evaluation of display group 33
• Evaluation of display group 32
• CHECKING OXYGEN SENSOR WIRING, HEATED OXYGEN SENSOR (HO2S) 2 -G108
• (cont.)
• Evaluation of display groups 037 and 038
• CHECKING OXYGEN SENSOR WIRING, OXYGEN SENSOR (O2S) BEHIND THREE WAY CATALYTIC CONVERTER (TWC) -G130
• CHECKING VOLTAGE SUPPLY FOR OXYGEN SENSOR HEATING
• WHEN INSTALLING, NOTE THE FOLLOWING POINTS
• INTAKE MANIFOLD CHANGE-OVER VALVE -N156- AND INTAKE MANIFOLD TUNING (IMT) VALVE 2 -N261-, CHECKING
• CHECKING VOLTAGE SUPPLY OF INTAKE MANIFOLD CHANGE-OVER VALVE/IMT VALVE 2
• CHECKING ACTUATION OF INTAKE MANIFOLD CHANGE-OVER VALVE/IMT VALVE 2
• INTAKE MANIFOLD CHANGE-OVER, CHECKING (A6 MODELS)
• CHECKING VACUUM SYSTEM FOR LEAKS
• INTAKE MANIFOLD CHANGE-OVER VALVE -N156- AND INTAKE AIR SWITCH-OVER VALVE -N335-, VACUUM DIAGRAM
• CONNECTING TEST BOX VAG 1598/31
• CHECKING VACUUM SYSTEM OF INTAKE AIR SWITCH-OVER VALVE -N335- FOR LEAKS
• ELECTRICAL CHECK FOR EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR VALVE -N80
• CHECKING SOLENOID VALVE VOLTAGE SUPPLY
• FUEL PUMP (FP) RELAY -J17- AND RELAY ACTUATION, CHECKING
• CHECKING EVAP CANISTER PURGE REGULATOR VALVE ACTUATION
• CHECKING ACTUATION OF SECONDARY AIR INJECTION PUMP RELAY
• Notes
• TEST CONDITIONS FOR ADAPTATION OF THE THROTTLE VALVE CONTROL MODULE
• CHECKING WIRING FOR VOLTAGE, SIGNAL AND ACTUATION
• CHECKING VOLTAGE SUPPLY FOR TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION
• CHECKING SIGNAL WIRING AND WIRING CONNECTIONS BETWEEN TP SENSOR/SENDER 2 FOR ACCELERATOR PEDAL POSITION AND ENGINE CONTROL MODULE
• Meaning of 4 digit readout of display zone 2
• IF THE VEHICLE SPEED IS NOT INDICATED.