Multiport Fuel Injection (mfi) - 4.2l v8 (akb, Aux, Ays) Audi A8 D3

Safety precautions

Observe the following precautions if test and measuring instruments are required during a road test

Rules for cleanliness

When working on the fuel supply/injection system, pay careful attention to the following rules for cleanliness

1. Thoroughly clean all connections and the adjacent areas before disconnecting.
2. Place parts that have been removed on a clean surface and cover them over. Do not use fluffy cloths.
3. Carefully cover or seal opened components if the repair cannot be completed immediately.
4. Only install clean components: Only unpack replacement parts immediately prior to installation. Do not use parts that have been stored loose (e.g. in tool boxes etc.).
5. When the fuel system is open: Do not work with compressed air if this can be avoided. Do not move vehicle unless absolutely necessary.
6. Disconnected electrical connectors: Keep clean and dry. Connect only when dry.

Technical data (A8 vehicles)

A8 TECHNICAL DATA (AKB/AUX 4.2L)

Technical data (S8 vehicles)

S8 TECHNICAL DATA (AYS 4.2L)

Component locations, overview

Components A to F are not shown in the exploded drawing.

1. Brake Light Switch -Fand Brake Pedal Switch -F47 - In footwell on pedal bracket near brake pedal
2. Diagnostic connector In front knee protection, driver side
3. Fuel Pump (FP) relay -J17- In electronics box in front passengers footwell, central electrics unit, relay position 4
4. Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position -G185- In footwell on accelerator pedal (both senders are installed in one housing)
5. Electronic Power Control (EPC) warning light In instrument cluster (Significance of light. See «ELECTRONIC ENGINE POWER CONTROL (EPC) WARNING LIGHT, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) )
6. Malfunction Indicator Light (MIL) In instrument cluster (Significance of light. See «EXHAUST MALFUNCTION INDICATOR LIGHT (MIL), SIGNIFICANCE»(ref-216437-S03499726612006020800000) )

Note. The following list refers to items in (Scheme 122).

1. Mass Air Flow (MAF) Sensor -G70- with Intake Air Temperature (IAT) Sensor -G42- In air cleaner filter element
2. Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80
3. Motronic Engine control Module (ECM) -J220- In E-box in plenum chamber, right side
4. Secondary Air Injection (AIR) Pump Relay -J299- In E-box in plenum chamber, right side
5. Valve -1- for camshaft adjustment -N205
6. 4-pin connector For Heated Oxygen Sensor (HO2S) -G39- and Oxygen Sensor (O2S) Heater -Z19 - Bank 1 NOTE: The 4-pin harness connector from Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Heated oxygen sensor -Z19- behind TWC bank 1 is located beneath the carpet at passenger side.
7. Engine Coolant Temperature (ECT) Sensor -G62- On coolant pipe behind cylinder head, Bank 1
8. 3 pin connector For Knock sensor (KS) 1 -G61
9. Fuel pressure regulator
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. 4 pin connector For Heated Oxygen Sensor (HO2S) 2 -G108 - and Oxygen Sensor (O2S) 2 Heater -Z28- bank 2 NOTE: The 4-pin harness connector from Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- and Heated oxygen sensor 2 -Z28- behind TWC bank 2 is located beneath the carpet at driver side.
12. 3 pin connector For Engine Speed (RPM) Sensor -G28
13. Secondary Air Injection (AIR) Solenoid Valve -N112
14. Camshaft Position (CMP) Sensor -G40- Cylinder bank 2
15. 3 pin connector For Knock Sensor (KS) 2 -G66
16. Ignition coils with power output stages Cylinder bank 2
17. Valve -2- for camshaft adjustment -N208
18. Intake Manifold Change -Over Valve -N156
19. Intake Manifold Tuning (IMT) Valve -2- -N261
20. Camshaft Position (CMP) Sensor 2 -G163- Cylinder bank 1
21. Ignition coils with power output stages Cylinder bank 1
22. Secondary Air Injection (AIR) Pump Motor -V101- In air cleaner housing

Scheme 122

Wiring and component check with VAG1598/31 test box

Note. If the Engine Control Module (ECM) is equipped with a metal anti-theft housing (for theft prevention), the metal anti-theft housing must be removed from the ECM to connect the test box. Procedure. See MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITH METAL ANTI -THEFT HOUSING), REPLACING . After repairs are complete, the metal anti-theft housing must be reinstalled. The VAG1598/31 test box is designed so it can be simultaneously connected to the control module wiring harness and to the control module itself. This has the advantage of enabling the engine management system to remain fully operational even with the test box connected (for example, when testing signals while the engine is running). The instructions for performing the individual tests indicate whether or not the engine control module itself also needs to be connected to the test box. Use the hand multimeter Fluke 83 (or equivalent) or the multimeter VAG1715 and the diode test lamp VAG1527B for the checks. To connect the testers to VAG1598/31 test box, always use the adapter leads from VAG1594 connector test kit.

Connecting VAG1598/31 test box

1. Switch off ignition.
2. Remove cover of E-box for control modules in plenum chamber, right side. To do this unscrew 7 screws (arrow). For the screw at right top in illustration unclip cover in vent grill.
3. Remove engine control module.
4. Release connectors on engine control module and disconnect connectors.
5. Connect VAG1598/31 test box to wiring harness connector. Also connect Ground (GND) clamp from test box to Ground (GND). Instructions for performing individual tests indicate whether or not engine control module itself also needs to be connected to test box.
6. Perform test as described in relevant repair instructions.

After installing the engine control module, perform the following operation

1. After re-connecting the engine control module, perform adaptation of engine control module to throttle valve control module. See «THROTTLE VALVE CONTROL MODULE, ADAPTATION»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__throttle-valve-control-module-adaptation) .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) .

Motronic Engine Control Module (ECM) -J220- (without metal anti -theft housing), replacing

Removing ECMs with metal anti -theft housing. See MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITH METAL ANTI -THEFT HOUSING), REPLACING .

Note. When the engine control module is disconnected the learned values are erased but the contents of the DTC memory remain intact.

Removing Engine Control Module (ECM)

1. Connect vehicle Diagnostic, Test and Information System VAS5051 or VAG1551 scan tool to vehicle and select control module for engine electronics "Address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . The ignition must be switched on.

Indicated on display: for example, ECM identification

Scheme 123

1. Always display ECM identification and print out.
2. Compare coding with coding variation table. See «CODING VARIATIONS OF ENGINE CONTROL MODULE (ECM)»(ref-216437-S28081866312006020800000) .
3. Switch ignition off.
4. Remove cover of electronics box for control modules in plenum chamber (right side).
5. Remove engine control module.
6. Release connectors on engine control module and disconnect connectors.
7. Take out old engine control module and install new one.

Installing engine control module

Installation is performed in the reverse sequence.

After installing new engine control module, perform the following operations

1. Code new engine control module. See «CODE CONTROL MODULE (FUNCTION 07) (ENGINE CODES AUX, AKB)»(ref-216437-S32627911612006020800000) .
2. Perform adaptation of immobilizer to engine control module See «ANTI-THEFT IMMOBILIZER, ON BOARD DIAGNOSTIC»(/audi/a8/d3-2002-2005/remont/collisionavoidance/#on-board-diagnostic-obd) .
3. Perform adaptation of Throttle Valve Control Module -J338-. See «THROTTLE VALVE CONTROL MODULE, ADAPTATION»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__throttle-valve-control-module-adaptation) .
4. On vehicles with cruise control (recognizable at steering column switch), activate cruise control function in engine control module. See «ACTIVATING CRUISE CONTROL SYSTEM (CCS)»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__activating-cruise-control-system-ccs) .
5. Check DTC memory and erase if necessary. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(ref-216437-S08471100802006020800000) .
6. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) .

Motronic Engine Control Module (ECM) -J220- (with metal anti -theft housing), replacing

Removing ECMs without metal anti -theft housing. See MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING .

Note. Adaptation values are erased when the harness connector is disconnected from the Engine Control Module (ECM). The Diagnostic Trouble Code (DTC) memory content remains intact.

Scheme 124

1. Connect VAS5051 tester and select vehicle system "01 - Engine Electronics". Ignition must be switched on for this.

VAS5051 tester display will indicate the control module identification and coding -2-.

Always allow display of control module identification first and print it out.

1. Switch ignition off.
2. Remove cover of E -box for control modules in plenum chamber (right side).
3. Remove Engine Control Module (ECM).

To restrict accessibility (for theft prevention) to the harness connectors and the Engine Control Module (ECM), the ECM -1- is screwed to a metal anti-theft housing -4- via a locking mechanism -2- and snap-off screws -3-.

Scheme 125

The threads of the snap -off screws are coated with locking compound to make it more difficult to remove the snap -off screws.

to disconnect the harness connectors from the Engine Control Module (ECM) (e.g. when connecting a test box or when replacing the ECM), the ECM must be removed from the metal anti-theft housing. This procedure is described as follows.

The following equipment is required

1. Heat gun -1- (from VAS1978 Wiring Harness Repair Kit)
2. Adapter nozzle -2- (also from VAS1978 Wiring Harness Repair Kit)
3. Standard locking pliers

Scheme 126

Procedure

Scheme 127

Scheme 128

1. "Flip" Engine Control Module (ECM) with anti -theft housing in direction of engine compartment so that locking mechanism (item -2- in illustration) becomes visible and place a clean rag below Engine Control Module (ECM) with anti -theft housing.
2. Adjust heat gun as shown in illustration, i.e. temperature adjustment -2- to maximum heat output and the two stage switch for air mass -3- to position 3.

Note. Next, use a heat gun to heat the threads of the locking mechanism in which the snap -off screws are screwed into. This step loosens the locking compound on the thread of the snap-off screws for easier removal.

Scheme 129

Scheme 130

1. Guide nozzle -1- of heat gun to locking mechanism threads so that nozzle "encloses" threads. It is OK to let nozzle make contact at upper end of metal anti -theft housing.
2. Switch on heat gun and heat up threads for approx. 20 to 25 seconds.
3. Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of arrow.

Note. Procedure for the second snap-off screw is exactly the same. Be very careful since the control module connector is in close proximity.

Scheme 131

Scheme 132

1. Guide nozzle -1- of heat gun to locking mechanism threads again so that nozzle "encloses" threads. It is OK to let nozzle make contact at upper end of metal anti - theft housing.
2. Switch on heat gun and heat up thread for approx. 20 to 25 seconds.
3. Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of arrow.

The Engine Control Module (ECM) can now be removed from the metal anti-theft housing.

1. Disengage connectors from Engine Control Module (ECM) and then disconnect connectors.
2. Remove old Engine Control Module (ECM) and insert new one.

Installing Engine Control Module (ECM)

Installation is the reverse order of removal, noting the following

After repairs are complete, the metal anti -theft housing must be reinstalled. Use new snap-off screws.

After connecting a new Engine Control Module (ECM), the following work steps must be performed

1. Activate Engine Control Module (ECM) in "Guided Troubleshooting" below the subject heading "Engine Control Module (ECM), replacing". Use VAS5051 tester to do so.

Motronic Engine Control Module (ECM) Power Supply Relay -J271-, checking

The Engine Control Module (ECM), ignition coils and valves for camshaft adjustment are powered via the ECM power supply relay, -J271-.

The ECM power supply relay -J271- will be activated with the ignition on.

Test conditions

1. Battery voltage OK

Checking activation of the ECM power supply relay

Note. The ECM power supply relay is located in the electronics box in the front passenger's footwell, (relay panel, relay position 2).

Scheme 133

1. Switch ignition off.
2. Connect VAG 1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831)

Specification: ECM power supply relay should be activated.

If the relay is now activated but not while switching ignition on

1. Replace Engine Control Module (ECM). See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .

If relay does not activate

1. Check voltage supply for the ECM power supply relay. See «ACTIVATING CRUISE CONTROL SYSTEM (CCS)»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__activating-cruise-control-system-ccs) .

Checking voltage supply for ECM power supply relay

1. Check fuse for ECM power supply relay -J271-. See SYSTEM WIRING DIAGRAMS .

If the fuse is not faulty

Scheme 134

Scheme 135

1. Remove ECM power supply relay from relay panel (relay position 2).
2. Connect hand-held multimeter (voltage measurement range) between Ground (GND) and terminal 4 on relay panel.

Specification: approx. battery voltage

If the specification is not obtained

1. Check wiring. See SYSTEM WIRING DIAGRAMS

If the specification is obtained

1. Test for open circuit and short to B+ or Ground (GND) in following wiring connection: ECM POWER SUPPLY RELAY TERMINALS WIRING CONNECTION Micro central electrics in passenger's footwell (right), relay position 2 terminal VAG1598/31 test box Socket 9 23
2. Repair any open/short circuit as necessary.

If no malfunction is detected in the wire

1. Replace ECM Power Supply Relay -J271-.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be regenerated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Activating Cruise Control System (CCS)

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.

Indicated on display

Scheme 136

1. Press button -1- twice to select "Log-in procedure" function and confirm entry with -Q- button.

Indicated on display

Scheme 137

1. Input code number 11463 and confirm entry with Q key.
2. Select (for measure of control) "address word" 01 to select control module for engine control module.

Indicated on display

Scheme 138

Test conditions

1. No leaks in exhaust system
2. Coolant temperature at least 85 °C (185 °F)
3. Electrical consumers switched off (coolant fan must not run during the check)
4. A/C switched off
5. Pressure gauge not connected
6. Selector lever in position P or N (vehicles with automatic transmission)

Checking idle speed

Note. The idle speed cannot be adjusted. The idle speed is tested during the basic setting of the engine. During the basic setting of the engine the A/C compressor is automatically switched off and the EVAP canister purge regulator valve is closed.

1. Check DTC memory. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(ref-216437-S08471100802006020800000) . DTC memory must be clear. If necessary, repair any malfunctions and erase DTC memory. Switch off engine, then start up again. Take vehicle for a test drive and check DTC memory again to make sure it is clear.
2. Run engine at idle speed.
3. Switch off A/C.
4. Switch off rear window heating.
5. Place selector lever in P or N position (automatic transmission).

Indicated on display

Scheme 139

1. Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

Indicated on display

Scheme 140

1. Press buttons -0- -5- and -6- to select "Display group number 056" and confirm entry with -Q- button.

Indicated on display: (1 - 4 display zones)

Scheme 141

1. Check whether engine speed shown in display zone 1 (actual engine speed) is within specified tolerance range (650 to 720 RPM). DISPLAY GROUP 056: IDLE SPEED STABILIZATION WITH ENGINE IDLING AT OPERATING TEMPERATURE Display fields 1 2 3 4 Display Group 056: Idle speed stabilization with engine idling at operating temperature Display xxx RPM xxx RPM x.x % 0 0 0 0 0 Indicates Engine speed (actual) Engine speed (specified) Idling speed control- torque change Operating conditions Work Range min.: 550 rpm max.: 6600 rpm min.: 550 RPM max.: 6600 RPM Specification 20 RPM higher or lower than figure in display field 2 650 to 720 RPM -1 to 1% 0 0 0 0 0 Note If readout does not match specification . See «If the idle speed is too high or too low, or if the engine does not idle smoothly, and there are no malfunctions stored in the DTC memory, perform the following tests (marked with dots)»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__if-the-idle-speed-is-too) Relevance of figures . See «Relevance of figures in 5-digit readout in Display Group 056»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__relevance-of-figures-in-5-digit-readout)

1. The value shown in display field 1 is the actual engine speed.
2. The value shown in display field 2 (specified engine speed) is a theoretical value calculated by the engine control module.
3. When the engine is idling the engine control module tries constantly to adjust the actual engine speed so that it matches the specified value.
4. This means that the actual engine speed when idling should always be approximately the same as the specified engine speed.
5. Display fields 3 and 4 provide additional information which is not relevant when checking the idle speed.

1. Press --> button.
2. Press buttons -0- and -6- to select function "End Output" and confirm entry with -Q- button.
3. If readout does not match specification, check DTC memory again.
4. If DTC memory was erased, generate readiness code. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

If the idle speed is too high or too low, or if the engine does not idle smoothly, and there are no malfunctions stored in the DTC memory, perform the following tests (marked with dots)

1. Check oxygen sensor learned values and oxygen sensor control. See «CHECKING OXYGEN SENSOR ADAPTATION AND OXYGEN SENSOR CONTROL»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-oxygen-sensor-adaptation-and-oxygen) .
2. Check for un-metered air (air leaks) in the intake system.
3. EVAP canister purge regulator valve constantly open, check. See «EVAPORATIVE EMISSION (EVAP) SYSTEM, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .
4. See «THROTTLE VALVE CONTROL MODULE, ADAPTATION»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__throttle-valve-control-module-adaptation) .

Relevance of figures in 5-digit readout in Display Group 056

RELEVANCE OF FIGURES IN 5-DIGIT READOUT IN DISPLAY GROUP 056

Requirements

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

Note. The fuel pressure regulator regulates the fuel pressure according to intake manifold pressure.

Scheme 142

1. Briefly open fuel tank filler cap (to release pressure).
2. Cover fuel pressurized connection with cloth.
3. Open connection (arrow) and catch escaping fuel with cloth.
4. Connect VAG1318 pressure tester with adapters VAG1318/6 and 1318/7 between fuel supply line and fuel rail.
5. Open cut -off valve on pressure tester (valve handle points in direction of flow).

Note. Pressure tester cut -off valve must be open (lever pointing in direction of flow).

1. Start engine and run at idle speed.
2. Measure fuel pressure. Specification: approx. 3.5 bar
3. Pull vacuum hose (arrow) off fuel pressure regulator.

Note. If fuel flows out at the vacuum connection on the fuel pressure regulator during the following pressure test, install a new fuel pressure regulator.

Fuel pressure must increase to approx. 4.0 bar.

If specification is not obtained

1. Install new pressure regulator as a trial measure and repeat the pressure test.
2. If fuel pressure still does not match specification, check fuel pump and supply line for damage (e.g. pinching) and replace if necessary.

If specification is obtained

1. Reconnect vacuum hose.
2. Switch ignition off.
3. Observe pressure drop on pressure gauge to check leakage and residual pressure. After 10 minutes pressure should still be at least 3 bar.

If holding pressure drops below 3.0 bar

1. Start engine and run at idle speed.
2. Switch ignition off after pressure has built up. At same time close cut -off valve on VAG1318 pressure gauge (valve handle at 90 to direction of flow).
3. Observe pressure drop on gauge.

If the pressure drops again, the following malfunctions are possible

1. Connections on pressure gauge downstream of cut -off valve leaking
2. Fuel pressure regulator defective
3. Injectors leaking

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

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

1. Check valve in fuel pump for leaking. See «FUEL SUPPLY SYSTEM»(/audi/a8/d3-2002-2005/remont/fuel-system/#fuel-supply-system-42l-v8-akb-aux-ays) .

1. Fuel pressure OK

Removing fuel rail

1. Remove engine compartment cover and remove intake air duct between air cleaner housing and throttle housing.
2. Disconnect vacuum hose from fuel pressure regulator.
3. Disconnect connectors for knock sensors and remove cable ties where necessary.
4. Disconnect solenoid valve for secondary air system from fuel rail.
5. Disconnect connectors from injectors and remove cable ties where necessary.
6. Unscrew fuel rail from intake manifold and lift fuel rail upward off intake manifold together with injectors.

Checking fuel injectors for leaks

1. Place fuel injector which is to be tested into a measuring glass from VAG1602 injection quantity tester.
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Bridge contacts 1 and 65 on test box using test leads from VAG1594A connector test kit. (This creates a Ground (GND) 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 happens for the following reason, when the ignition is switched on the fuel pump relay receives a positive voltage supply via the central electrics. The Ground (GND) connection for the fuel pump relay is created via the jumper wire on the test box.

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

Scheme 143

1. Place fuel injector which is to be tested into a measuring glass from VAG1602 injection quantity tester.
2. Connect one of fuel injector terminals to engine Ground (GND) using test lead and alligator clamp from VAG1594A connector test kit.
3. Connect second fuel injector terminal to B+ using VAG1348/3A remote control, VAG1348/3 -2 adapter cable and auxiliary cable. (Scheme 151)
4. Switch ignition on. Fuel pump should run.
5. Activate VAG1348/3A remote control for 30 seconds.
6. Perform measurement on all fuel injectors.
7. When all fuel injectors have been actuated, place measuring glasses on level surface. Specification: 95 to 115 ml at each fuel injector

If none of the fuel injectors delivers the specified quantity

1. Check fuel pressure. See «FUEL PRESSURE REGULATOR AND RESIDUAL FUEL PRESSURE, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .

If only one fuel injector fails to deliver the specified quantity

1. Replace malfunctioning fuel injector.

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

Installation of the fuel rail 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 not to remove the plastic cap from the injector head. The O-ring must be pulled off over the plastic cap.
2. Moisten the O-rings with clean engine oil.
3. Check to make sure that the retainer clamps are properly seated.

Scheme 144

1. Disconnect harness connector from injector to be tested.
2. Connect hand-held multimeter to fuel injector (resistance measurement range). Specification: 13 to 16ohm

Note. When the engine is at operating temperature the electrical resistance of the injectors will be about 4 to 6 ohm higher.

If the specification is not obtained

1. Replace fuel injector.

If specification is met

1. See «CHECKING VOLTAGE SUPPLY»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-voltage-supply) .

Scheme 145

1. Disconnect harness connector from fuel injector to be tested.
2. Connect diode test lamp (for measuring voltage) between Ground (GND) and socket 1 of connector.
3. Operate starter for few seconds (the engine can be allowed to start). Specification: Diode test lamp should light up.

If the diode test lamp lights up

1. See «CHECKING WIRING CONNECTIONS»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-wiring-connections) .

If the diode test lamp does not light up

Scheme 146

1. Test for continuity in the wiring from socket 1 to fuel pump relay via fuse for injectors. If necessary, repair open circuit. See SYSTEM WIRING DIAGRAMS .

Scheme 147

1. Switch ignition off.
2. Disconnect harness connector from injector to be tested.
3. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
4. Test for open circuit and short to B+ or Ground (GND) in the following wiring connections: FUEL INJECTOR CIRCUIT - OPEN CIRCUIT & SHORT TO GROUND CHECK Cylinder 2-pin connector on wiring harness, socket VAG1598/31 test box, socket 1 2 96 2 2 19 3 2 113 4 2 88 5 2 97 6 2 112 7 2 24 8 2 89
5. Repair any open/short circuit as necessary. See SYSTEM WIRING DIAGRAMS .
6. If wiring is OK, install new engine control module. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .

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

The fuel pump and some of the injection system components are powered via the fuel pump relay -J17-.

The Fuel Pump (FP) relay -J17- will only be activated if the engine is turning over. That means, the relay is only grounded (via the engine control module) when the engine control module is receiving engine speed impulses.

1. Battery voltage OK

Functional test of fuel pump relay

Note. The fuel pump relay is located in the electronics box in the front passenger's footwell (central electrics unit, relay position 4).

Scheme 148

Scheme 149

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.
2. Start output Diagnostic Test Mode (DTM). See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) . Fuel pump relay should activate and fuel pump should run.

If the relay does not activate

1. See «TESTING ACTIVATION OF FUEL PUMP RELAY»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__testing-activation-of-fuel-pump-relay) .

If fuel pump does not run

1. See «CHECKING ACTIVATION FOR FUEL PUMP AND COMPONENTS»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .

Testing activation of fuel pump relay

1. Switch ignition off.
2. Connect VAG1598/31 test box to wiring harness for engine control unit. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Connect sockets 65 and 2 of test box to each other using test leads from VAG1594 connector test kit. Specification: Fuel pump relay (relay position 4) should be activated.

If the relay is now activated but not during the output Diagnostic Test Mode (DTM)

1. Replace Engine Control Module (ECM). See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .

If the relay does not activate

Scheme 150

Scheme 151

1. Disconnect fuel pump relay from relay panel (relay position 4).
2. Connect hand-held multimeter (voltage measurement range) between Ground (GND) and terminal 19 on relay panel. Specification: approx. battery voltage

If the specification is not obtained

1. Check wiring. See SYSTEM WIRING DIAGRAMS .

If the specification is obtained

Scheme 152

1. Test for open circuit and short to B+ or Ground (GND) in the following wiring connection: FUEL PUMP RELAY CIRCUIT TEST - ACTIVATION Micro central electrics in passenger's footwell (right), relay position 4 terminal VAG1598/31 test box Socket 16 65
2. Repair any open/short circuit as necessary.

If no malfunction is detected in the wire

1. Replace Fuel Pump (FP) Relay -J17-.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be regenerated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Scheme 153

1. Remove fuse cover on A-pillar in footwell on right side.
2. Remove fuses 1, 2 and 3 (in blue fuse carrier, 4th row from the top).
3. Start output Diagnostic Test Mode (DTM). See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .
4. Connect hand-held multimeter (voltage measurement range) between Ground (GND) and either left or right contact of following fuses (only one fuse terminal voltage supply): FUEL PUMP RELAY FUSE SPECIFICATIONS Fuse No. Specification for left or right contact 1 approx. battery voltage 2 approx. battery voltage 3 approx. battery voltage

If the specifications are not obtained

1. Check wiring. See SYSTEM WIRING DIAGRAMS .

If no malfunction is detected in wire

1. Replace Fuel Pump (FP) Relay -J17-.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be regenerated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

1. Coolant temperature at least 80 °C (175 °F)
2. Electrical consumers switched off (coolant fan must not run during test)
3. A/C switched off
4. Fuse for Mass Air Flow (MAF) sensor OK See SYSTEM WIRING DIAGRAMS

Checking function

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 154

1. Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

Note. During the basic setting the engine control module closes the EVAP canister purge regulator valve -N80- and switches off the A/C compressor.

Indicated on display

Scheme 155

1. Press buttons -0-, -0- and -2- to select Display Group 002 and confirm entry with -Q- button.

Indicated on display

Scheme 156

1. Check displayed specified values for engine load. DISPLAY GROUP 002: INTAKE AIR MASS AT IDLING SPEED WITH ENGINE AT OPERATING TEMPERATURE Display fields 1 2 3 4 Display Group 002: Intake air mass at idling speed with engine at operating temperature Display xxx RPM xx.x % x.x ms xxx.x g/s Indicates Engine speed (in steps of 40 RPM) Load Average injection period Air mass Work range min.: 550 rpm max.: 6600 rpm min.: 0% max.: 110% Specification 650 to 720 rpm 14.0 to 20.0% 1.0 to 5.0 ms 3.5 to 7.0 g/s Note - - If readout does not match specification, see table for display field 3. See «READING DISPLAY GROUP 002»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__reading-display-group-002) If readout does not match specification, see table for display field 4. See «Reading Display Group 002»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__reading-display-group-002)

If the specification is obtained

1. Press -> button.
2. Press buttons -0- and -6- to select function "End Output" and confirm entry with -Q- button.
3. Switch ignition off.

Reading Display Group 002

READING DISPLAY GROUP 002

Scheme 157

1. Disconnect harness connector from MAF sensor.
2. Connect hand-held multimeter (voltage measurement range) between engine Ground (GND) and socket 2 of connector.
3. Operate starter briefly. Specification: approx. battery voltage

Note. The MAF sensor receives its voltage supply via the fuel pump relay.

If the reading does not match the battery voltage

1. Check for open circuit or short to Ground (GND) in wiring between fuel pump relay and socket 2 on connector via fuse. Repair if necessary. See SYSTEM WIRING DIAGRAMS .

If specification is met

1. Check Ground (GND) connection from control module. See «CHECKING GROUND (GND) CONNECTION»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .

Scheme 158

1. Connect hand-held multimeter (voltage measurement range) between sockets 2 and 3 of connector.
2. Operate starter briefly. Specification: approx. battery voltage

Note. Socket 3 on the connector is the Ground (GND) connection from the engine control module.

If the specification is not attained

Scheme 159

1. Check wiring. See «CHECKING WIRING FOR MAF SENSOR»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-wiring-for-maf-sensor) .
2. Connect hand-held multimeter (voltage measurement range) between sockets 3 and 4 of connector.
3. Switch ignition on. Specification: approx. 5 V

If the specification is not attained

1. Check wiring. See «CHECKING WIRING FOR MAF SENSOR»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-wiring-for-maf-sensor) .

Checking wiring for MAF sensor

Note. The wiring test includes also testing the signal wire.

Scheme 160

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
2. Check for open circuit and short to B+ or Ground (GND) in following wiring connections: MAF SENSOR CIRCUIT TEST - OPENS/SHORTS Connector for MAF sensor - G70, socket VAG1598/31 test box, socket 3 27 4 53 5 (signal wire) 29 Resistance in wiring: max. 1.5ohm
3. Repair short circuit or open circuit if necessary. See SYSTEM WIRING DIAGRAMS .
4. Also check for short circuits between all wires. MAF SENSOR CIRCUIT TEST - SHORTS BETWEEN ALL WIRES Connector for MAF sensor -G70-, socket VAG1598/31 test box, socket 3 53 and 29 4 27 and 29 5 (signal wire) 27 and 53 Specification: infinity ohm (open circuit)
5. If wiring and voltage supply are OK, replace Mass Air Flow (MAF) sensor -G70-.
6. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be regenerated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

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

For loocation of sensor, see COMPONENT LOCATIONS, OVERVIEW . MAF sensor and intake air temperature sensor are combined as one component in air filter.

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.

Indicated on display

Scheme 161

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Scheme 162

1. Press buttons -0-, -0- and -4- to select Display Group 4 and confirm entry with -Q- button.

Indicated on display: (1 - 4 display fields)

Scheme 163

1. Check display value for intake air temperature sensor (display field 4): DISPLAY GROUP 4: INTAKE AIR TEMPERATURE WITH ENGINE IDLE Display fields 1 2 3 4 Display Group 4: Intake air temperature with engine idle Display xxxx RPM xx.xxx V xxx.x °C xxx.x °C Indicates Engine speed Battery voltage Coolant temperature Intake air temperature Work range min.: 550 RPM max.: 6600 RPM min.: 0.000 V max.: 15.000 V Specification 650 to 720 RPM 12.000 to 14.500 V 80.0 to 110.0 °C Between ambient temperature and 50 °C 1) Note If the display shows a temperature that differs excessively from surrounding temperature, test wiring . See «CHECKING WIRING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays)

Scheme 164

Scheme 165

1. Switch ignition off.
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Disconnect harness connector from MAF sensor. See «COMPONENT LOCATIONS, OVERVIEW»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__component-locations-overview) .
4. Check for short circuit between wires: IAT SENSOR CIRCUIT TEST - SHORTS 5-pin connector on wiring harness, socket VAG1598/31 test box, socket 1 27 Specification: infinity ohm (open circuit)
5. Check for open circuit and short to B+ or Ground (GND) in following wiring connections: IAT SENSOR CIRCUIT TEST - OPENS/SHORTS 5-pin connector on wiring harness, socket VAG1598/31 test box, socket 1 85 3 27 Resistance in wiring: max. 1.5 ohm
6. Repair any open/short circuit as necessary.

If no wiring malfunction is detected

1. Replace Intake Air Temperature (IAT) sensor -G42-.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

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

Component location of Engine Coolant Temperature (ECT) sensor -G62-. See COMPONENT LOCATIONS, OVERVIEW .

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool to vehicle and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 166

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q-button.

Indicated on display

Scheme 167

1. Press buttons -0-, -0- and -4- to select Display Group 4 and confirm entry with -Q- button.

Indicated on display

Scheme 168

1. Check readout for ECT sensor in display field 3. DISPLAY GROUP 4: COOLANT TEMPERATURE WITH ENGINE IDLE Display fields 1 2 3 4 Display Group 4: Coolant temperature with engine idle Display xxxx RPM xx.xxx V xxx.x °C xxx.x °C Indicates Engine speed (in steps of 40 RPM) Battery voltage Coolant temperature Intake air temperature Range min.: 550 RPM max.: 6600 RPM min.: 0.000 V max.: 15.000 V Specification 650 to 720 RPM 12.000 to 14.500 V 80.0 to 105.0 °C Ambient temperature Note The temperature readout should increase steadily If specification is not obtained, test sensor or sensor wiring . See «TESTING WIRING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays)

Scheme 169

1. Switch ignition off.
2. Disconnect harness connector from sensor.
3. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
4. Check wiring from 4-pin connector to engine control module for open circuit or short circuit to B+ or Ground (GND). ECT SENSOR CIRCUIT TEST - OPENS/SHORTS 4-pin connector on wiring harness, socket VAG1598/31 test box, socket 3 108 4 93 Resistance in wiring: max. 1.5ohm
5. Repair any open/short circuit as necessary.

If no wiring malfunction is detected

1. Replace Engine Coolant Temperature (ECT) Sensor -G62-.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Oxygen sensor control, function

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 too rich" (low residual oxygen) is between about 0.5 and 1.0 V (relative to reference Ground (GND)).

The voltage signal for "Mixture too lean" (high residual oxygen) is between about 0 and 0.5 V (relative to reference Ground (GND)).

The transition from "rich" to "lean" is accompanied by a voltage jump from between 0.5 and 1.0 V to between 0 and 0.5 V (relative to reference Ground (GND)), and vice versa ("lambda" = 1.0).

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 (GND) = preset Ground (GND) from Engine Control Module (ECM).

If the voltage does not change or only changes slowly the following malfunctions are possible

1. Slits or holes in probe head are blocked.
2. Oxygen sensor has been subjected to excessive thermal stress.
3. Contact resistance in signal wire or Ground (GND) wire.
4. Oxygen sensor too cold; sensor heater not working.
5. Oxygen sensor damaged by contact spray or similar product. (The contact spray is drawn through the fine cavities in the electrical wiring as a result of thermal fluctuations and capillary effect.)
6. 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.)

Scheme 170

1. Fluke 83 (or equivalent) A
2. VAG1594 A
3. VAG1598/31
4. VAS5051 with VAS5051/1 - or
5. VAG1551 with VAG1551/3 A

Note. For the defined troubleshooting procedure, it is possible to switch off the oxygen sensor control by selecting Display Group 99 in "Basic Setting" mode and to switch it on again by selecting Display Group 99 in "Read Measuring Value Block" mode. After selecting Display Group 99 (either in "Basic Setting" mode or in "Read Measuring Value Block" mode) it is possible to switch back and forth between function 04 ("Basic Setting") and function 08 "Read Measuring Value Block") by pressing buttons 4 and 8 on VAG1551 scan tool. When exiting the "Basic Setting" mode (function 04) the oxygen sensor control is automatically switched on again.

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 VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 171

1. Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

Note. During the basic setting the Evaporative Emission (EVAP) canister purge regulator valve -N80- is closed and the A/C compressor is switched off.

Indicated on display

Scheme 172

1. Press buttons -0-, -3- and -0- to select "display group number 030" and confirm entry with -Q- button.

Indicated on display: (1 - 4 display fields)

Scheme 173

1. Check oxygen sensor status in display fields 1 to 4.

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

DISPLAY GROUP 30: OXYGEN SENSOR STATUS AT IDLE SPEED

Note. Significance of display. See SIGNIFICANCE OF 3 DIGIT INDICATION IN DISPLAY GROUP 30 . If specification is obtained, but a malfunction is stored in the DTC memory: Check oxygen sensor adaptation values and oxygen sensor control. See CHECKING OXYGEN SENSOR ADAPTATION AND OXYGEN SENSOR CONTROL . If specification is not obtained: Check oxygen sensor signal wire and activation. See OXYGEN SENSOR SIGNAL WIRE AND ACTIVATION, CHECKING .

Significance of 3 digit indication in Display Group 30

SIGNIFICANCE OF 3 DIGIT INDICATION IN DISPLAY GROUP 30

Checking oxygen sensor adaptation and oxygen sensor control

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be idling.

Indicated on display

Scheme 174

1. Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

Note. During the basic setting the Evaporative Emission (EVAP) canister purge regulator valve -N80- is closed and the A/C compressor is switched off.

Indicated on display

Scheme 175

1. Press buttons -0-, -3- and -3- to select Display Group 33 and confirm entry with -Q- button.

Indicated on display: (1 - 4 display fields)

Scheme 176

1. Check oxygen sensor control in display fields 1 to 4: DISPLAY GROUP 33: OXYGEN SENSOR CONTROL AT IDLE SPEED Display fields 1 2 3 4 Display Group 33: Oxygen sensor control at idle speed Display xx.x % xx.x V xx.x % xx.x V Indicates Oxygen sensor control, bank 1 Oxygen sensor voltage, bank 1 Oxygen sensor control, bank 2 Oxygen sensor voltage, bank 2 Work range min.: -25.0% max.: 25.0% min.: 0.000 Volt max.: 1.000 Volt min.: -25.0% max.: 25.0% min.: 0.000 Volt max.: 1.000 Volt Specification -10.0 to 10.0 % (The value must fluctuate by 2%) Between 0.000 and 1.000 V the voltage should fluctuate -10.0 to 10.0 % (The value must fluctuate by 2%) Between 0.000 and 1.000 V the voltage should fluctuate Note If readout does not match specification. See «EVALUATION DISPLAY GROUP 33»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-33) If readout does not match specification. See «EVALUATION DISPLAY GROUP 33»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-33) If readout does not match specification. See «EVALUATION DISPLAY GROUP 33»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-33) If readout does not match specification. See «EVALUATION DISPLAY GROUP 33»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-33)
2. Press button -C-.
3. Press buttons -0-, -3- and -3- to select Display Group 33 and confirm entry with -Q- button.

Indicated on display: (1 - 4 display fields)

Scheme 177

1. Check oxygen sensor control in display fields 1 to 4: DISPLAY GROUP 32: OXYGEN SENSOR ADAPTATION AT IDLE SPEED Display fields 1 2 3 4 Display Group 32: Oxygen sensor adaptation at idle speed Display xx.x % x.xxx % xx.x % x.xxx % Indicates Oxygen sensor adaptation value, bank 1, sensor 1 at idle (additive) Oxygen sensor adaptation value, bank 1, sensor 1 at partial throttle (multiple) Oxygen sensor adaptation value, bank 2, sensor 1 at idle (additive) Oxygen sensor adaptation value, bank 2, sensor 1 at partial throttle (multiple) Range min.: -25.0% max.: 25.0% min.: -25.0% max.: 25.0% min.: -25.0% max.: 25.0% min.: -25.0% max.: 25.0% Specification -5.7 and 5.7% can fluctuate slightly -15.0 and 15.0% can fluctuate slightly -5.7 and 5.7% can fluctuate slightly -15.0 and 15.0% can fluctuate slightly Note If readout does not match specification. See «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-32) and «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) If readout does not match specification. See «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-32) and «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) If readout does not match specification. See «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-32) and «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) If readout does not match specification. See «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-32) and «EVALUATION DISPLAY GROUP 32»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays)

If the specified values in display fields 1 and/or 3 do not match the specifications, or if the readout does not fluctuate by at least 2 %

1. Check oxygen sensor heater. See «OXYGEN SENSOR HEATER FOR OXYGEN SENSOR, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__oxygen-sensor-heater-for-oxygen-sensor) .
2. See «OXYGEN SENSOR SIGNAL WIRE AND ACTIVATION, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__oxygen-sensor-signal-wire-and-activation) .
3. Check intake system for leaks and eliminate unmetered air.
4. Check fuel pressure regulator. See «FUEL PRESSURE REGULATOR AND RESIDUAL FUEL PRESSURE, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .
5. Check if fuel return line is kinked or plugged.
6. Press --> button.
7. Press button -0- and -6- to select function "End Output" and confirm with -Q- button.
8. Switch ignition off.

Evaluation display group 32

EVALUATION DISPLAY GROUP 32

EVALUATION DISPLAY GROUP 32

Evaluation display group 33

EVALUATION DISPLAY GROUP 33

Test requirements

1. Coolant temperature min. 85 °C (185 °F)

Test sequence for oxygen sensor 1 before catalytic converter bank 1

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 178

1. Press buttons -0- and -4- to select "Basic Setting" and confirm with -Q- button.

Indicated on display

Scheme 179

1. Press -0-, -3- and -4- to select "display group number 034" and confirm with -Q- button.

Indicated on display

Scheme 180

1. Continue test as soon as display 4 indicates "Test ON".

Note. This procedure can take a few minutes

DISPLAY FIELD 034: DIAGNOSTIC OXYGEN SENSOR AGING (BANK 1)

Note for display field 2

Calculated value from engine speed and engine load.

Note for display fields 3 and 4

Period duration is the time between two voltage jumps (e.g. rich - lean - rich) and is therefore a measurement of the aging condition of the oxygen sensor. If the specified time is exceeded, display field 4 will indicate =B1 -S1 not OK.

Continuation

If specified value in display field 3 or 4 is not obtained

1. Replace Heated Oxygen Sensor (HO2S) before Three Way Catalytic Converter Bank 1 -G39-.

Test sequence for oxygen sensor 1 before catalytic converter bank 2

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 181

1. Press buttons -0- and -4- to select "Basic Setting" and confirm with -Q- button.

Indicated on display

1. Press -0-, -3- and -5- to select "display group number 035" and confirm with -Q- button.

Indicated on display

Scheme 182

1. Continue test as soon as display 4 indicates "Test ON".

Note. This procedure can take a few minutes.

DISPLAY FIELD 035: DIAGNOSTIC OXYGEN SENSOR AGING (BANK 2)

Note for display field 2

Calculated value from engine speed and engine load.

Note for display fields 3 and 4

Period duration is the time between two voltage jumps (e.g. rich - lean - rich) and is therefore a measurement of the aging condition of the oxygen sensor. If the specified time is exceeded, display field 4 will indicate =B2 -S1 not OK.

If specified value in display field 3 or 4 is not obtained

1. Replace Heated Oxygen Sensor (HO2S) before Three Way Catalytic Converter Bank 2 -G108 -.

Scheme 183

1. Fluke 83 (or equivalent)
2. VAG1594 A
3. VAG1598/31
4. VAG1788/10
5. VAS5051 with VAS5051/1 - or
6. VAG1551 with VAG1551/3 A

Note. Oxygen sensor control behind the catalytic converter is responsible for final control correction. It is the primary sensor and can override the signal from the oxygen sensor control before the catalytic converter. It corrects slight changes in the mixture (i.e. enrichment) via the oxygen sensor before catalytic converter by holding the oxygen sensor control before catalytic converter at its higher or lower limit for a specific time (duration). If this time is in the positive range (i.e. 50 ms), mixture is shifted in the -enrich- direction. If this time is in the negative range (i.e. -50 ms), mixture is shifted in the -lean- direction.

Scheme 184

Component location of connectors for oxygen sensors 2 behind catalytic converter

The harness connector for Oxygen sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130 - is located beneath the carpet on passenger side.

Scheme 185

The harness connector for Oxygen sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131 - is located beneath the carpet on driver side.

Scheme 186

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 VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 187

1. Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

Note. During the basic setting the Evaporative Emission (EVAP) canister purge regulator valve -N80- is closed and the A/C compressor is switched off.

Indicated on display

Scheme 188

1. Press buttons -0-, -3- and -4- to select "display group number 034" and confirm entry with -Q- button.

When indicated on display

Scheme 189

1. Adjust engine speed using VAG1788/10 to 2800 - 3200 RPM.
2. Continue test as soon as display field 2 indicates an exhaust temperature of more than 200 °C.

Note. This process can take a few minutes.

1. Press -C- button.
2. Adjust engine speed using VAG1788/10 to 1900 - 2400 RPM.

When indicated on display

Scheme 190

1. Press buttons -0-, -3- and -0- to select "display group number 030" and press -Q- button to confirm input.

When indicated on display

Scheme 191

1. Check oxygen sensor status for oxygen sensor behind catalytic converter in display field 2.

Note. "Oxygen sensor status" indicates status of oxygen sensor control and oxygen sensor.

DISPLAY GROUP 30: OXYGEN SENSOR STATUS WITH ENGINE AT IDLE

Note. Oxygen sensor control of oxygen sensor behind catalytic converter (Bank 1 -Sensor 2 and Bank 2 -Sensor 2) is not active without engine load. The first position of the 3 digit indication (heater) fluctuates between 0 and 1. The third position of the 3 digit indication (oxygen sensor control) fluctuates between 0 and 1.

SIGNIFICANCE OF 3 DIGIT INDICATION IN DISPLAY GROUP 30

1. Press -C- button. Increase engine speed until exhaust temperature 250 °C is reached (display group 34, display field 2)

When indicated on display

Scheme 192

1. Press buttons -0-, -4- and -3- to select "display group number 043" and press -Q- button to confirm input.

When indicated on display

Scheme 193

1. Check specified value in display field 4. DISPLAY GROUP 043: OXYGEN SENSOR AGING OXYGEN SENSOR BEHIND CATALYTIC CONVERTER (BANK 1) Display fields 1 2 3 4 Display group 043: Oxygen sensor aging oxygen sensor behind catalytic converter (Bank 1) Display xxxx/RPM xxx °C x.xxx V Test ON Indicated Engine speed (RPM) Exhaust temperature Voltage of oxygen sensor behind CAT, Bank 1 Diagnostic condition Work range 0 to 6800/RPM 70 to 850 °C 0.000 to 1.000 Volt Test OFF Test ON B1-S2 OK B1-S2 not OK Specified value 650 to 720/RPM approx. 250 °C 0.000 to 1.000 Volt B1-S2 OK Note If specified value is not reached. Check oxygen sensor heater. See «OXYGEN SENSOR HEATER FOR OXYGEN SENSOR, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__oxygen-sensor-heater-for-oxygen-sensor)

If the specified value of "B1 -S2 OK" is reached

1. Press -C- button.
2. Press buttons -0-, -4- and -4- to select "display group number 044" and press -Q- button to confirm input. DISPLAY GROUP 044: OXYGEN SENSOR AGING OXYGEN SENSOR BEHIND CATALYTIC CONVERTER (BANK 2) Display fields 1 2 3 4 Display group 044: Oxygen sensor aging oxygen sensor behind catalytic converter (Bank 2) Display xxxx/RPM xxx °C x.xxx V Test ON Indicated Engine speed (RPM) Exhaust temperature Voltage of oxygen sensor behind CAT, Bank 1 Diagnostic condition Work range 0 to 6800/RPM 70 to 850 °C 0.000 to 1.000 Volt Test OFF Test ON B2-S2 OK B2-S2 not OK Specified value 650 to 720/RPM approx. 250 °C 0.000 to 1.000 Volt B1-S2 OK Note If specified value is not reached. Check oxygen sensor heater. See «OXYGEN SENSOR HEATER FOR OXYGEN SENSOR, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__oxygen-sensor-heater-for-oxygen-sensor)

If the specified value of "B2-S2 OK" is reached

1. Press -C- button.

Checking oxygen sensor control behind catalytic converter

1. Perform road test for approx. 10 minutes.

Indicated on display

Scheme 194

1. Press buttons -0-, -3- and -7- to select "display group number 037" and press -Q- button to confirm input.

Indicated on display

Scheme 195

1. Check oxygen sensor voltage in display field 2.
2. Check dwell time (hold up) between oxygen sensor 1 before catalytic converter and oxygen sensor 2 behind catalytic converter in display field 3 and diagnostic result in display field 4. DISPLAY GROUP 037: DIAGNOSTIC OXYGEN SENSOR CONTROL (BANK 1) Display fields 1 2 3 4 Display group 037: Diagnostic oxygen sensor control (Bank 1) Display xxx % x.xxx Volt xxx ms Test ON Indicated Engine load Oxygen sensor voltage behind catalytic converter, Bank 1 Correction value between oxygen sensor 1 and sensor 2, bank 1 Diagnostic condition Work range 15 to 150% 0.000 to 1.000 V -1200 to 1200 ms Test OFF Test ON SYSTEM OK SYSTEM not OK Specified value 13.5 to 22.5% 0.1 to 1.000 V -200 to 200 ms SYSTEM OK Note If specified value is not obtained: Evaluation display field 2. See «EVALUATION DISPLAY GROUP 037 AND 038»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__evaluation-display-group-037-and-038) If specified value is obtained:. See «CONTINUATION»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) If "SYSTEM not OK" is displayed: Check DTC memory. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(ref-216437-S08471100802006020800000) or continue. See «CONTINUATION»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .

Note for display field 3

Oxygen sensor control behind catalytic converter is superior to oxygen sensor control before catalytic converter and is the primary control. It corrects slight changes in the mixture (i.e. enrichment or thinning) by holding the oxygen sensor control before catalytic converter at its higher or lower point for a specific time (duration). If this time is in the positive range (i.e. 50 ms), mixture is shifted in the -enrich- direction. If this time is in the negative range (i.e. 50 ms), mixture is shifted in the -lean- direction.

1. Press -C- button.
2. Press buttons -0-, -3- and -8- to select "display group number 038" and press -Q- button to confirm input.

Indicated on display: (1 - 4 = display fields)

Scheme 196

DISPLAY GROUP 038: DIAGNOSTIC OXYGEN SENSOR CONTROL (BANK 2)

Note for display field 3

Oxygen sensor control behind catalytic converter is superior to oxygen sensor control before catalytic converter and is the primary control. It corrects slight changes in the mixture (i.e. enrichment or thinning) by holding the oxygen sensor control before catalytic converter at its higher or lower point for a specific time (duration). If this time is in the positive range (i.e. 50 ms), mixture is shifted in the -enrich- direction. If this time is in the negative range (i.e. 50 ms), mixture is shifted in the -lean- direction.

Evaluation display group 037 and 038

EVALUATION DISPLAY GROUP 037 AND 038

If the specified value in display group 037 and 038, display 3 or 4 is not obtained

1. Check exhaust system and catalytic converter for leaks (check clamps and exhaust for damage)
2. Replace particular oxygen sensor before catalytic converter.

Oxygen sensor heater for oxygen sensor, checking

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

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 197

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Scheme 198

1. Press buttons -0-, -4- and -1- to select "display group number 041" and confirm entry with -Q- button.

Indicated on display

Scheme 199

1. Check resistance of oxygen sensor heater. DISPLAY GROUP 41: OXYGEN SENSOR HEATER, BANK 1 (AT IDLE SPEED) Display fields 1 2 3 4 Display Group 41: Oxygen sensor heater, Bank 1 (at idle speed) Display xxx kOhm Htg.bC.ON xxx kOhm Htg.aC.ON Indicates Bank 1, Sensor 1 Status of heater Bank 1, Sensor 2 Status of heater Range Htg.bC.ON Htg.bC.OFF Htg.aC.ON Htg.aC.OFF Specified value 0 to 0.9 kOhm Htg.bC.ON 0.0 to 0.9 kOhm Htg.aC.ON Note It can take a few minutes until specified values are obtained
2. Press -C- button.
3. Press buttons -0-, -4- and -2- to select "display group number 042" and confirm entry with -Q- button. DISPLAY GROUP 042: OXYGEN SENSOR HEATER, BANK 2 (AT IDLE SPEED) Display fields 1 2 3 4 Display Group 042: Oxygen sensor heater, Bank 2 (at idle speed) Display xxx kOhm Htg.bC.ON xxx kOhm Htg.aC.ON Indicates Bank 2, Sensor 1 Status of heater Bank 2, Sensor 2 Status of heater Range Htg.bC.ON Htg.bC.OFF Htg.aC.ON Htg.aC.OFF Specified value 0 to 0.9 kOhm Htg.bC.ON 0 to 0.9 kOhm Htg.aC.ON Note It can take a few minutes until specified values are obtained

If the specification is not attained

1. See «CHECKING VOLTAGE SUPPLY FOR OXYGEN SENSOR HEATER»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-voltage-supply-for-oxygen-sensor) .
2. See «OXYGEN SENSOR SIGNAL WIRE AND ACTIVATION, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__oxygen-sensor-signal-wire-and-activation) .

Checking voltage supply for oxygen sensor heater

Component location of 4-pin harness connector of oxygen sensors. See COMPONENT LOCATIONS, OVERVIEW .

Scheme 200

1. Check fuse for oxygen sensor heater. See SYSTEM WIRING DIAGRAMS .
2. Disconnect 4-pin harness connector of particular oxygen sensor.
3. Connect hand-held multimeter (voltage measurement range) between sockets 1 (B+) and 2 (Ground (GND)) using test leads from VAG1594 connector test kit.
4. Operate starter briefly. Specification: approx. battery voltage

If there is no voltage reading

1. Connect hand-held multimeter (voltage measurement range) between socket 1 (B+) and vehicle Ground (GND) using test leads from VAG1594 connector test kit.
2. Operate starter briefly. Specification: approx. battery voltage

If there is still no voltage reading

1. Check for open circuit and/or short circuit in wiring between fuel pump relay and socket 1 on the relevant oxygen sensor connector (on wiring harness) via fuse. See SYSTEM WIRING DIAGRAMS .

If the voltage supply is OK

Scheme 201

1. Connect hand-held multimeter (voltage measurement range) between socket 2 (switched Ground (GND) connection from engine control module) and battery positive terminal using test leads from VAG1594 connector test kit.
2. Start engine. Specification: approx. battery voltage (fluctuating)

Note. At certain points in the operating range the engine control module continuously "switches" the Ground (GND) connection to the oxygen sensor heater. That means, it repeatedly connects and disconnects the Ground (GND) connection at these points. For this reason the voltage reading on the tester may fluctuate.

1. Switch ignition off.

If there is no voltage reading

Scheme 202

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
2. Check for open circuits in the following wiring connection: CHECKING OXYGEN SENSOR HEATER CIRCUIT - OPENS Heated Oxygen Sensor (HO2S) -G39- Connector on wiring harness, socket VAG1598/31 test box, socket 2 5 (Ground) Heated Oxygen Sensor (HO2S) 2 -G108 - Connector on wiring harness, socket VAG1598/31 test box, socket 2 4 (Ground) Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130 - Connector on wiring harness, socket VAG1598/31 test box, socket 2 63 (Ground) Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131 - Connector on wiring harness, socket VAG1598/31 test box, socket 2 6 (Ground)

Resistance in wiring: max. 1.5 Ohm

See SYSTEM WIRING DIAGRAMS .

If the wiring is OK but the oxygen sensor heater still has no Ground (GND) connection

1. Replace particular oxygen sensor.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be regenerated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Oxygen sensor signal wire and activation, checking

Note. The oxygen sensor signal is monitored by the OBD system.

1. Check DTC memory. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(ref-216437-S08471100802006020800000) .
2. If malfunction related to oxygen sensor is displayed and oxygen sensor heater is OK, disconnect harness connector for relevant oxygen sensor.

Component location of 4-pin harness connector of oxygen sensor. See COMPONENT LOCATIONS, OVERVIEW .

Scheme 203

1. Test voltage by connecting hand-held multimeter Fluke 83 (or equivalent) (measuring range 2 V) between sockets 3 and 4 of connector on wiring harness.
2. Switch ignition on. Specification: 450 50 mV.

If the specification is not obtained, check oxygen sensor wiring

Bank 1, Sensor 1. See CHECKING OXYGEN SENSOR WIRING FOR HEATED OXYGEN SENSOR (HO2S) -G39 .

Bank 1, Sensor 2. See CHECKING WIRING FOR OXYGEN SENSOR (O2S) BEHIND THREE WAY CATALYTIC CONVERTER (TWC) -G130 .

Bank 2, Sensor 1. See CHECKING WIRING FOR HEATED OXYGEN SENSOR (HO2S) 2 -G108 .

Bank 2, Sensor 2. See CHECKING WIRING FOR OXYGEN SENSOR (O2S) 2 BEHIND THREE WAY CATALYTIC CONVERTER (TWC) -G131 .

If specification is obtained

1. Replace relevant oxygen sensor.

Checking oxygen sensor wiring for Heated Oxygen Sensor (HO2S) -G39

Component location of 4-pin harness connector of oxygen sensor. See COMPONENT LOCATIONS, OVERVIEW .

Scheme 204

Scheme 205

1. Disconnect 4-pin connector (black) for Heated Oxygen Sensor (HO2S) -G39-.
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Check following wiring connections for open circuits: HO2S G39 - OPEN CIRCUIT CHECK Connector on wiring harness, socket VAG1598/31 test box socket 3 51 4 70 Resistance in wiring: max. 1.5 Ohm See SYSTEM WIRING DIAGRAMS .
4. Check wiring on 4-pin connector for short circuits to each other. HO2S G39 - SHORT CIRCUIT TO EACH OTHER Connector on wiring harness, socket VAG1598/31 test box socket 4 51 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .
5. Check shielded wire for short circuit to sensor wiring. HO2S G39 - SHORT CIRCUIT TO SENSOR WIRING Connector on wiring harness, socket VAG1598/31 test box socket 4 32 3 32 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .

If no malfunctions are identified in the wiring

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .

Checking wiring for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130

Component location of 4-pin harness connector of oxygen sensor. See COMPONENT LOCATIONS, OVERVIEW .

Scheme 206

Scheme 207

1. Disconnect 4-pin connector (black) for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-.
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Check following wiring connections for open circuits: HO2S G130 BEHIND TWC - OPEN CIRCUIT CHECK Connector on wiring harness, socket VAG1598/31 test box socket 3 68 4 69 Resistance in wiring: max. 1.5 ohm See SYSTEM WIRING DIAGRAMS .
4. Check wires on 4-pin connector for short circuits with each other. HO2S G130 BEHIND TWC - SHORT CIRCUIT WITH EACH OTHER Connector on wiring harness, socket VAG1598/31 test box socket 4 68 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .
5. Check shielded wire for short circuit to sensor wiring. HO2S G130 BEHIND TWC - SHORT CIRCUIT TO SENSOR WIRING Connector on wiring harness, socket VAG1598/31 test box socket 4 32 3 32 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .

If no malfunctions are identified in the wiring

1. Replace Motronic Engine Control Module (ECM) -J220. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .

Checking wiring for Heated Oxygen Sensor (HO2S) 2 -G108

Component location of 4-pin harness connector of oxygen sensor. See COMPONENT LOCATIONS, OVERVIEW .

Scheme 208

Scheme 209

1. Disconnect 4-pin connector (black) for Heated Oxygen Sensor (HO2S) 2 -G108-.
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Check following wiring connections for open circuits: HO2S 2 G108 - OPEN CIRCUIT CHECK Connector on wiring harness, socket VAG1598/31 test box socket 3 12 4 13 Resistance in wiring: max. 1.5 ohm See SYSTEM WIRING DIAGRAMS .
4. Check wires on 4-pin connector for short circuits to each other. HO2S 2 G108 - SHORT CIRCUIT TO EACH OTHER Connector on wiring harness, socket VAG1598/31 test box socket 4 12 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .
5. Check shielded wire for short circuit to sensor wiring. HO2S 2 G108 - SHORT CIRCUIT TO SENSOR WIRING Connector on wiring harness, socket VAG1598/31 test box socket 4 32 3 32 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .

If no malfunctions are identified in the wiring

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .

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

Component location of 4-pin harness connector of oxygen sensor. See COMPONENT LOCATIONS, OVERVIEW .

Scheme 210

Scheme 211

1. Disconnect 4-pin connector for Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Check following wiring connections for open circuits: HO2S 2 BEHIND TWC G108 - OPEN CIRCUIT CHECK Connector on wiring harness, socket VAG1598/31 test box socket 3 10 4 11 Resistance in wiring: max. 1.5 ohm See SYSTEM WIRING DIAGRAMS .
4. Check wires on 4-pin connector for short circuits to each other. HO2S 2 BEHIND TWC G108 - SHORT CIRCUIT TO EACH OTHER Connector on wiring harness, socket VAG1598/31 test box socket 4 10 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .
5. Check shielded wire for short circuit to sensor wiring. HO2S 2 BEHIND TWC G108 - SHORT CIRCUIT TO SENSOR WIRING Connector on wiring harness, socket VAG1598/31 test box socket 4 32 3 32 Specification: infinite ohms (open circuit) See SYSTEM WIRING DIAGRAMS .

If no malfunctions are identified in the wiring

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .

If no malfunction can be identified in the wiring

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be regenerated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Scheme 212

1. Disconnect harness connector of particular oxygen sensor before catalytic converter for bank 1 and bank 2 (See «COMPONENT LOCATIONS, OVERVIEW»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__component-locations-overview) ).
2. Disconnect harness connector of particular oxygen sensor behind catalytic converter for bank 1 and bank 2 (See «COMPONENT LOCATIONS, OVERVIEW»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__component-locations-overview) ).
3. Remove left or right exhaust pipe with catalytic converter. See «EXHAUST SYSTEM, EMISSION CONTROLS - 4.2L V8 (2L V8 (AKB, AUX, AYS) - A8 & S8»(ref-196867) .
4. Remove particular oxygen sensor with 3337/9 special tool.

When installing observe the following

Note. The wiring from the oxygen sensor must be fastened at the exact location as previously installed, to avoid contact with exhaust pipe. The oxygen sensor threads are coated with a thread sealing compound that must not come in contact with the slits in the sensor tip. Tightening torque: 50 Nm (37 ft lb)

Intake manifold change-over, checking (A8 vehicles)

This test should only be carried out if the vehicle has a performance problem or if a malfunction is stored in the DTC memory.

The intake manifold change-over between the long intake tract and the short intake tract is controlled according to engine speed and engine load.

Intake manifold change-over, checking function

1. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 213

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Scheme 214

1. Press buttons -0-, -9- and -5- to select "display group 095" and confirm entry with -Q- button.

Indicated on display

Scheme 215

Scheme 216

1. Check specific display values for intake manifold change-over. DISPLAY GROUP 095: INTAKE MANIFOLD CHANGE -OVER AT IDLE SPEED (A8) Display fields 1 2 3 4 Display Group 095: Intake manifold change -over at idle speed Display xxx RPM x.xx % xxx.x °C IMC-V OFF Indicates Engine speed (in steps of 40 RPM) Load Coolant temperature Intake manifold change-over Range min.: 550 RPM max.: 6600 RPM min.: 0.00% max.: 110.00% IMC-V OFF Stage 1 Stage 2 Specified value 650 to 720 RPM 14 to 20% 80.0 to 105.0 °C IMC-V OFF Note Both vacuum units should pull in
2. Check readout in display field 4. Specification: "IMC-V OFF"

Increase engine RPM to the following figures to activate the intake manifold change-over function.

INTAKE MANIFOLD CHANGE-OVER FUNCTION (A8)

DISPLAY GROUP 095: INTAKE MANIFOLD CHANGE -OVER WITH VEHICLE BEING DRIVEN (A8)

1. Check whether correct vacuum unit is actuated at particular engine speed.

If the display shows "Stage 1 or 2" but the intake manifold change -over is not activated (vacuum units must drop back), test the following components

1. Check intake manifold change -over valves. See «INTAKE MANIFOLD CHANGE -OVER VALVE -N156- AND INTAKE MANIFOLD TUNING (IMT) VALVE -2- -N261-, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__intake-manifold-change-over-valve-n156) .

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.
2. Switch engine off.
3. Switch ignition on.
4. Perform output Diagnostic Test Mode (DTM) and activate solenoid valves for intake manifold change-over. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .

Indicated on display

Scheme 217

Indicated on display

Scheme 218

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

Scheme 219

If one of the valves does not click.

Scheme 220

1. Switch ignition off.
2. Disconnect harness connector from relevant intake manifold change -over solenoid valve.
3. Measure resistance between valve contacts using Fluke 83 (or equivalent) multi meter. Specification: 25 to 35 ohm
4. If reading does not match the specification, replace intake manifold change-over valve.

If the reading matches the specification, check voltage supply. See CHECKING VOLTAGE SUPPLY TO INTAKE MANIFOLD CHANGE-OVER VALVE .

Checking voltage supply to intake manifold change-over valve

1. Connect VAG1527B diode test lamp between engine Ground (GND) and socket 1 on connector using test leads from VAG1594 connector test kit.
2. Operate starter briefly. Diode test lamp should light up.

If diode test lamp does not light up

1. Check fuse for intake manifold change-over valve. See SYSTEM WIRING DIAGRAMS .

If fuse is OK

1. Check for open circuit and short circuit in wiring between fuel pump relay and socket 1 on connector via fuse for intake manifold change -over valve. See SYSTEM WIRING DIAGRAMS .

If the voltage supply is OK, check activation. See CHECKING ACTIVATION OF INTAKE MANIFOLD CHANGE-OVER VALVE .

1. Re-install fuel pump relay and fuse.

Scheme 221

Scheme 222

1. Connect VAG1527B diode test lamp between sockets 1 (B+) and 2 on connector for intake manifold change -over valve using test leads from VAG1594 connector test kit.
2. Perform output Diagnostic Test Mode (DTM) and activate relevant intake manifold change-over valve. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) . Indicated on display Indicated on display

If diode test lamp does not flash or lights up continuously, check wiring. See CHECKING ACTIVATION OF INTAKE MANIFOLD CHANGE-OVER VALVE .

Scheme 223

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .

Test the following wiring connections for open circuits and short to B+ or Ground (GND).

INTAKE MANIFOLD CHANGE-OVER VALVE CONTACTS WIRING CONNECTIONS (A8)

Resistance in wiring: max. 1.5 ohm.

See SYSTEM WIRING DIAGRAMS .

If wiring is OK.

1. Replace Engine Control Module (ECM). See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .
2. Check intake manifold change -over function again. See «INTAKE MANIFOLD CHANGE-OVER, CHECKING (A8 VEHICLES)»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__intake-manifold-change-over-checking-a8-vehicles) .
3. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be regenerated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Scheme 224

1. Remove relevant intake manifold change-over valve.
2. Disconnect connector from intake manifold change-over valve.
3. Connect one of contacts on the solenoid valve to engine Ground (GND) using test leads and alligator clamp from VAG1594 connector test kit.
4. Connect other contact on the solenoid valve to positive using remote control VAG1348/3A, adapter lead VAG 348/3-2 and auxiliary cable.
5. Operate remote control VAG1348/3A.
6. Blow into connection and check whether valve is opening properly.

If the valve does not open

1. Replace relevant intake manifold change-over valve.

If no malfunctions are found in the tests performed up to this point

1. Re-install intake manifold change -over valve.
2. See «CHECKING VACUUM SYSTEM FOR LEAKS»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-vacuum-system-for-leaks) .

Checking vacuum system for leaks

1. Disconnect vacuum hoses from relevant vacuum unit for intake manifold change-over system.
2. Connect hand-held vacuum pump VAG1390 to vacuum unit.
3. Operate hand -held vacuum pump and check whether change-over function is working.
4. Test vacuum unit for leaks. (Vacuum unit should not return to "rest" position while a vacuum is being maintained via hand pump.)

If the vacuum unit returns to its "rest" position

1. Replace vacuum unit. If the vacuum unit is airtight, check all vacuum hoses for leaks.

Intake manifold change -over valve, checking function

The first stage of the intake manifold change-over is not available on any S8 vehicle.

This test should only be performed if there is a performance deficiency of if a malfunction is stored.

The intake manifold change-over from the long intake path to the short path is RPM dependent.

1. Connect VAS5051 tester or VAG1551 scan tool and select the control module for engine electronics via "address word" 01. See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must run at idle for this.

Indicated on display

Scheme 225

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

Indicated on display

Scheme 226

1. Press buttons -0-, -9- and -5- to select "Display group number 95" and press -Q- button to confirm input.

Indicated on display

Scheme 227

Scheme 228

Scheme 229

1. Check specified value for intake manifold change -over. DISPLAY GROUP 95: INTAKE MANIFOLD CHANGE -OVER AT IDLE (S8) Display fields 1 2 3 4 Display group 95: Intake manifold change -over at idle Display xxx /min x.xx % xxx.x °C IM-CO OFF Indicated Engine speed (RPM) (in increments of 40) Load Coolant temperature Intake manifold change-over Functional range min.: 550 RPM max.: 7200 RPM min.: 0.00 % max.: 110.00 % IM-CO OFF IM-CO ON Specified value 600 to 820 RPM 14 to 24 % 80.0 to 105.0 °C IM-CO OFF Note Vacuum diaphragms must be activated Specified value in display field 4: "SU -V OFF" vacuum diaphragms pulled in
2. Increase engine speed to approx. 5400 RPM to initiate intake manifold change-over. DISPLAY GROUP 95: INTAKE MANIFOLD CHANGE -OVER IN DRIVING MODE (S8) Display fields 1 2 3 4 Display group 95: Intake manifold change -over in driving mode Display xxxx/min xx.xx % xxx.x °C IM-CO ON Indicated Engine speed (RPM) (in increments of 40) Load Coolant temperature Intake manifold changeover Functional range min.: 550 RPM max.: 7200 RPM min.: 0.00 % max.: 110.00 % IM-CO OFF IM-CO ON Specified value xxxx/min xx.xx % 80.0 to 105.0 °C IM-CO ON Note
3. Check whether vacuum diaphragms are being activated.

If "SU-V ON" is indicated, but the intake manifold change-over is not being initiated (vacuum diaphragms must release), check the following components

1. Check solenoid valves for intake manifold change-over. See «INTAKE MANIFOLD CHANGE -OVER VALVE - N156-, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__intake-manifold-change-over-valve-n156) .

Intake manifold change-over valve - N156-, checking

1. Let vehicle run at idle for 2 to 3 minutes (vacuum build-up).
2. Switch off engine.
3. Switch ignition on.
4. Perform Output Diagnostic Test Mode (DTM) and activate intake manifold change-over valves. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .

Indicated on display

Scheme 230

Solenoid valve must click (by touch or audibly). Output Diagnostic Test Mode (DTM) will be aborted after one minute.

1. Solenoid valve does not click.
2. Switch ignition off.
3. Disconnect connector from solenoid valve for intake manifold change-over.
4. Perform a resistance measurement between solenoid valve terminals using VAG1526.

Specification: 25 to 35 Ohm

1. If specified value is not reached, replace intake manifold change-over valve.

If the specified value is obtained, check voltage supply.

Checking voltage supply of intake manifold change-over valve

1. Connect VAG1527B voltage tester to connector socket 1 and engine Ground (GND) using adapter cables from VAG1594 connector test kit.
2. Operate starter briefly.

LED must light up.

1. LED does not light up.
2. Check fuse for intake manifold change -over valve. See SYSTEM WIRING DIAGRAMS .

Voltage supply is OK.

1. Wire connection from connector socket 1 via fuse for intake manifold change-over valve to fuel pump relay for open circuit or short circuit. See SYSTEM WIRING DIAGRAMS .

Scheme 231

If the voltage supply is OK, check activation.

1. Re-install fuel pump relay and fuse.

Checking activation of intake manifold change-over valve

1. Connect VAG1527B voltage tester using cables from VAG1594 connector test kit to sockets 1 (B+) and 2 of connector to intake manifold change-over valve.
2. Perform output Diagnostic Test Mode (DTM) and activate respective intake manifold change-over valve. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .

Indicated on display

Scheme 232

If LED does not blink or if it remains constantly lit. Check wire connection.

Scheme 233

1. Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .

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

INTAKE MANIFOLD CHANGE-OVER VALVE CIRCUIT TEST - OPENS/SHORTS (S8)

Wire resistance: max: 1.5 Ohm

See SYSTEM WIRING DIAGRAMS .

1. If the wire connection is OK, replace Engine Control Module (ECM).
2. Check intake manifold change-over once again for function. See «INTAKE MANIFOLD CHANGE-OVER, CHECKING (A8 VEHICLES)»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__intake-manifold-change-over-checking-a8-vehicles) .

Checking solenoid valve for throughput and proper seal

1. Remove intake manifold change -over valve.
2. Disconnect connector from intake manifold change-over valve to be checked.
3. Connect one terminal of solenoid valve to engine Ground (GND) using an adapter cable and an alligator clip from VAG1594 connector test kit.
4. Connect second terminal of solenoid valve to B+ using VAG1348/3A remote control, VAG1348/3 -2 adapter cable and assisting cable.
5. Operate VAG1348/3A remote control.
6. Check whether solenoid valve opens properly by blowing into connection.

If one solenoid valve does not open.

1. Replace intake manifold change-over valve.

If no malfunction was recognized for all previous tests.

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

Checking vacuum system for proper seal

1. Disconnect vacuum hoses from vacuum reservoir for intake manifold change -over.
2. Connect VAG1390 hand vacuum pump to vacuum reservoir.
3. Operate hand vacuum pump and observe change-over procedure.
4. Check vacuum reservoir for proper seal. (Vacuum reservoir must not return to rest position, as long as hand vacuum pump is not vented.)

If the vacuum diaphragm moves back.

1. Replace vacuum diaphragm.

If the vacuum diaphragm has no leaks, check all vacuum hoses for proper seal.

Checking for leaks

If there is no electrical signal (not activated) the solenoid valve remains closed.

1. Disconnect hoses from Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-.
2. Connect an auxiliary test hose to one of the connections on (EVAP) Canister Purge Regulator Valve.
3. Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.
4. Start output Diagnostic Test Mode and select Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .

Indicated on display

Scheme 234

Valve should click and should open and close (test by blowing into auxiliary hose).

1. If valve does not click, perform «ELECTRICAL TESTING OF EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR VALVE -N80»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .
2. If valve does not open and close properly, replace Evaporative Emission (EVAP) Canister Purge Regulator Valve.

Scheme 235

1. Disconnect connector from Evaporative Emission (EVAP) Canister Purge Regulator Valve-N80-.
2. Measure resistance between contacts on valve using hand -held multimeter Fluke 83 (or equivalent). Specification: 22 to 30 ohm

If the specification is not obtained

1. Replace Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-.

If the specification is obtained

1. Check voltage supply. See «CHECKING POWER SUPPLY TO SOLENOID VALVE»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-power-supply-to-solenoid-valve) .

Checking power supply to solenoid valve

Note. The Evaporative Emission (EVAP) Canister Purge Regulator Valve receives its power supply via the fuel pump relay.

1. Check fuse for Evaporative Emission (EVAP) Canister Purge Regulator Valve. See SYSTEM WIRING DIAGRAMS .

If the fuse is OK

Scheme 236

1. Disconnect harness connector on Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-.
2. Connect VAG1527B diode test lamp between engine Ground (GND) and socket 1 on connector.
3. Operate starter. Diode test lamp should light up.

If diode test lamp does not light up

1. Check continuity of wiring from socket 1 to fuel pump relay via fuse. Repair open circuit if necessary. See SYSTEM WIRING DIAGRAMS .
2. If wiring is OK, check fuel pump relay. See «FUEL PUMP (FP) RELAY -J17- AND RELAY ACTIVATION, CHECKING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__fuel-pump-fp-relay-j17-and) .

If the diode test lamp lights up, check activation. See TESTING ACTIVATION OF EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR VALVE .

Scheme 237

1. Connect VAG1527B between diode test lamp sockets 1 (B+) and 2 of harness connector.
2. Start output Diagnostic Test Mode (DTM) and select Evaporative Emission (EVAP) Canister Purge Regulator Valves -N80-. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) . Diode test lamp should blink.

If the diode test lamp does not blink or lights up continuously

1. Connect VAG1598/31 test box to multi -pin harness connector for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .

If the diode test lamp lights up continuously

1. Check for short circuit to Ground (GND) in following wiring connections: EVAP CANISTER PURGE REGULATOR VALVE CIRCUIT TEST - SHORT CIRCUIT TO GROUND CHECK 2-pin connector on wiring harness, socket VAG1598/31 test box, socket 2 64

If the diode test lamp does not flash

Scheme 238

1. Test for short to B+ or open circuit in following wiring connections: VAP CANISTER PURGE REGULATOR VALVE CIRCUIT TEST - SHORT TO B+ OR OPEN CIRCUIT CHECK 2-pin connector on wiring harness, socket Test box VAG 1598/31, socket 2 64 Resistance in wiring: max. 1.5 ohm See SYSTEM WIRING DIAGRAMS .
2. If necessary, repair short circuit to Ground (GND) or open circuit.

If no short circuit or open circuit is found

1. Replace Motronic Engine Control Module (ECM) -J220. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Secondary Air Injection (AIR) Solenoid Valve -N112-, checking

Component location of secondary air injection valve. See COMPONENT LOCATIONS, OVERVIEW

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.
2. Start output Diagnostic Test Mode (DTM) and activate secondary air injection valve. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .

Indicated on display

Scheme 239

Secondary air injection valve should click.

If the secondary air injection valve does not click

1. Disconnect 2-pin harness connector from valve.
2. Connect VAG1527B diode test lamp to disconnected connector using test leads from VAG1594 connector test kit.
3. Repeat output DTM.

If the diode test lamp now blinks during the DTM

1. Replace secondary air injection valve.

If the diode test lamp still does not flash

1. Switch ignition off.
2. Connect VAG1598/31 test box to wiring harness for engine control unit. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Check for open circuit in following wiring connection: SECONDARY AIR INJECTION (AIR) VALVE CIRCUIT TEST - OPEN CIRCUIT CHECK Socket of 2-pin connector on wiring harness Socket on VAG1598/31 test box 2 44 Resistance in wiring: max. 1.5 ohm See SYSTEM WIRING DIAGRAMS .

If no malfunction in wire is detected

1. Test voltage supply to secondary air injection valve using wiring diagram. See SYSTEM WIRING DIAGRAMS .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

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

Note. The secondary air pump relay is located in the electronics box in the plenum chamber.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.
2. Start output Diagnostic Test Mode (DTM) and activate secondary air pump relay. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .

Indicated on display

Scheme 240

Secondary Air Injection (AIR) Pump Relay -J299- activates Secondary Air Injection (AIR) Pump Motor -V101-, which runs at intervals until the DTM is terminated by pressing the button.

If Secondary Air Injection (AIR) Pump Motor -V101- does not run at intervals

1. Disconnect 2-pin harness connector from secondary air pump motor and connect VAG1527B diode test lamp to disconnected connector using test leads from VAG1594 connector test kit.
2. Repeat output DTM.

If the diode test lamp now blinks during DTM

1. Replace Secondary Air Injection (AIR) Pump Motor -V101-.

If diode test lamp does not blink and secondary air injection pump relay does not click, see CHECK ACTIVATION OF SECONDARY AIR INJECTION PUMP RELAY .

If diode test lamp does not flash but secondary air pump relay clicks, test voltage supply for secondary air injection pump relay.

Checking voltage supply for secondary air pump relay

1. Check fuse for Secondary Air Injection (AIR) Pump Relay -J299-. See SYSTEM WIRING DIAGRAMS .

If the fuse is not faulty

Note. The secondary air pump relay is located in the electronics box in the plenum chamber.

1. Remove secondary air pump relay from relay carrier. See SYSTEM WIRING DIAGRAMS .
2. Test voltage supply (positive 30) for relay. See SYSTEM WIRING DIAGRAMS .

If no malfunctions are identified in the voltage supply for the relay.

1. Replace Secondary Air Injection (AIR) Pump Relay -J299-.

Check activation of secondary air injection pump relay

1. Switch ignition off.
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .

Note. The secondary air injection pump relay is located in the electronics box in the plenum chamber.

1. Remove secondary air injection pump relay from relay carrier. See SYSTEM WIRING DIAGRAMS .
2. Check for open circuit in following wiring connection: SECONDARY AIR INJECTION PUMP RELAY CIRCUIT TEST - OPEN CIRCUIT CHECK Secondary air pump relay, contact Socket on VAG1598/31 test box See SYSTEM WIRING DIAGRAMS . 46 Resistance in wiring: max. 1.5 ohm

If no malfunction in wire is detected

1. Replace Motronic Engine Control Module (ECM) -J220-. See «MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__motronic-engine-control-module-ecm-j220) .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Electronic throttle system, function

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

The position of the accelerator pedal is communicated to the engine control module by two accelerator position sensors (variable resistors, both installed in a single housing) which are connected to the accelerator pedal.

The accelerator position (as determined by the driver) is one of the main input values for the engine control module.

The throttle valve is actuated by a servomotor (throttle valve positioner) in the throttle valve control part over the full range of engine speeds and load conditions.

The throttle valve positioner actuates the throttle valve according to the commands it receives from the engine control module.

When the engine is running (i.e. under load) the engine control module can open and close the throttle valve freely (i.e. independently of the signals being sent by the accelerator position sender).

The electronic throttle is not simply a combination of two or three components, but rather a complete system comprising all the elements that together determine the position of the throttle valve and also control and monitor it. For example, the accelerator position sensor, throttle valve control module, EPC warning lamp, engine control module etc.

Throttle valve control module -J338-, checking

The housing for the throttle valve control part contains the following components (the housing must not be opened)

1. Throttle drive -G186 - (power accelerator actuation) (This is an electric motor activated by the engine control module. The motor opens the throttle valve by applying force to overcome the spring pressure.)
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 resistors). Each sends its own separate signal to inform the engine control module of the position of the throttle valve (i.e. one of the signals is redundant). The potentiometers cannot be adjusted mechanically. Settings are made using the "Basic Setting" function (function 04) with vehicle diagnostic, testing and information system VAS5051 or with VAG1551 scan tool.

Throttle valve control module, adaptation

The adaptation process enables the engine control module to learn the different 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 angle sensors for throttle valve drive.

If the Throttle Valve Control Module -J338- or the engine control module is removed and installed or replaced, or if the power supply to the engine control module is interrupted, an adaptation must be performed.

The learning process (adaptation process) is carried out

1. By selecting "Basic Setting" (function 04), Display Group 60 with the ignition switched on.
2. Automatically if the ignition is switched on for at least 6 seconds without operating the starter or depressing the accelerator, and if the engine control module registers a "learning requirement." (In this case, however, there is no way of knowing whether the adaptation process was successful or not.) The engine control module will register a learning requirement if the previously stored voltage readings from the angle sensors do not correspond (within a certain tolerance range) to the new voltage readings.

Test conditions for adaptation of throttle valve control module

1. No malfunctions stored in DTC memory. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(ref-216437-S08471100802006020800000) .
2. Accelerator pedal not depressed
3. Coolant temperature between 5 °C and 105 °C
4. Intake air temperature above 5 °C
5. Voltage supply to engine control module more than 11 V, Testing. See «CONTROL MODULE VOLTAGE SUPPLY, CHECKING»(ref-216439-S02356686132006020800000) .

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . When doing this ignition must be switched on.

Indicated on display

Scheme 241

1. Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

Indicated on display

Scheme 242

1. Press buttons -0-, -6- and -0- for Display Group 060 and confirm entry with -Q- button.

Indicated on display

Scheme 243

When the -Q- button is pressed the throttle valve positioner will be switched mechanically.

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

The throttle valve is then opened by a predetermined amount. As soon as it reaches this position the current supply to the throttle valve positioner is again disconnected. The spring should then close the throttle valve mechanically to the previously learned default position within a specified period of time (spring test).

The throttle valve positioner then closes the throttle valve and 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 current supply to the throttle valve positioner while the vehicle is being driven, the result will be an increase in idling speed with fluctuating engine RPM (hunting) and very slow throttle response.

1. Check display readout for throttle valve control module (display fields 3 and 4). DISPLAY GROUP 060: ADAPTATION OF THROTTLE VALVE CONTROL MODULE WITH IGNITION ON (1 OF 2) Display fields 1 2 3 4 Display Group 060: Adaptation of throttle valve control module with ignition on Display xx % xx % - - Indicates Throttle valve angle (angle sensor 1) Throttle valve angle (angle sensor 2) Learning stage counter Adaptation status Work Range min.: 0% max.: 100% min.: 0% max.: 100% 0 or 8 ADP. runs ADP. OK. ADP. ERROR Specified value 10 to 20% 80 to 90% Learning stage counter must run from 0 to 8 during adaptation process (some digits may also skip). ADP runs Note If specification is not met: See «Throttle valve control module, adaptation notes»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__throttle-valve-control-module-adaptation-notes) .
2. Check display readout for throttle valve control module (display fields 3 and 4). DISPLAY GROUP 060: ADAPTATION OF THROTTLE VALVE CONTROL MODULE WITH IGNITION ON (2 OF 2) Display fields 1 2 3 4 Display Group 060: Adaptation of throttle valve control module with ignition on Display xx % xx % - - Indicates Throttle valve angle (angle sensor 1) Throttle valve angle (angle sensor 2) Learning stage counter Adaptation status Work Range min.: 0% max.: 100% min.: 0% max.: 100% 0 or 8 ADP. runs ADP. OK. ADP. ERROR Specified value xxx % xxx % 8 ADP OK. Note If specification is not met: See «Throttle valve control module, adaptation notes»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__throttle-valve-control-module-adaptation-notes) .

Throttle valve control module, adaptation 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: All test conditions must be met. See TEST CONDITIONS FOR ADAPTATION OF THROTTLE VALVE CONTROL MODULE . The engine was started or the accelerator depressed during the adaptation process. The throttle valve is unable to close completely (e.g. because of dirt) 6-pin harness connector not properly to throttle valve control module connected. Wiring is faulty. Distortion of throttle valve housing (check bolts) Throttle valve control module faulty.

1. End engine basic setting by pressing -->button.
2. Press buttons -0- and -6- to select "End Output" function and confirm input with -Q- button.

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

The angle sensor -1- for throttle drive (power accelerator actuation) -G187 - and angle sensor - 2- for throttle drive (power accelerator actuation) -G188- inform the engine control module of the position of the throttle valve. Both angle sensors are located in the throttle valve control module.

If a malfunction relating to angle sensor -1- for throttle drive (power accelerator actuation) -G187 - and angle sensor -2- for throttle drive (power accelerator actuation) -G188- is stored in the DTC memory, test voltage supply to throttle valve control module.

Checking voltage supply to throttle valve control module

1. Check fuse for throttle valve control module. See SYSTEM WIRING DIAGRAMS .

If the fuse is OK

Scheme 244

1. Disconnect harness connector from throttle valve control module.
2. Switch ignition on.
3. Connect hand-held multimeter (voltage range) between following sockets on connector: THROTTLE VALVE CONTROL MODULE PIN CIRCUIT TEST - VOLTAGE CHECK 6-pin connector on wiring harness, socket Specification 2 + Ground (GND) approx. 5 V 2 + 6 approx. 5 V

If the specifications are not obtained, test wiring connections from engine control module to throttle valve control module. See Checking wiring for voltage, signal and activation .

If the readouts match the specifications, test also the signal wires and activation wires for the throttle valve positioner. See Checking wiring for voltage, signal and activation .

Scheme 245

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .

Test following wiring connections for open circuits and short to B+ or Ground (GND).

THROTTLE VALVE CONTROL MODULE PIN CIRCUIT TEST - OPEN CIRCUITS & SHORT TO GROUND

Resistance in wiring: max. 1.5 ohm

1. Repair any open/short circuit as necessary. See SYSTEM WIRING DIAGRAMS .

If no wiring fault is detected

1. Replace throttle valve control module. See SYSTEM WIRING DIAGRAMS .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Electronic Engine Power Control (EPC) warning light in instrument cluster, significance

"EPC" stands for Electronic Power Control and refers to the electronic throttle control system.

Component location of EPC warning light

Scheme 246

The engine control module switches the EPC warning light on when the ignition is switched on.

After the engine has been started, the engine control module tests all important parts of the electronic throttle control system for functionality.

During the test sequence the EPC warning light comes on for about 3 seconds. If a malfunction is detected during this test phase the malfunction indictor light will remain lit.

If a malfunction is detected in the electronic throttle system while the engine is running, the engine control module will activate the EPC warning lamp (see DTC Table for list of possible malfunctions). At the same time a DTC code is stored in the DTC memory of the engine control module.

Checking function of warning light

1. Start engine. Specification: If no malfunctions relating to electronic throttle are stored in DTC memory, EPC warning light should light up for about 3 seconds after engine is started.

If the EPC malfunction indicator light does not light up

1. Check wiring from engine control module to EPC warning light in instrument cluster as follows: See SYSTEM WIRING DIAGRAMS .
2. Check DTC memory of engine control module. See «DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING»(ref-216437-S08471100802006020800000) .
3. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

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

The Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position -G185 - are located at the accelerator pedal. Both sensors inform (completely independently of the other) the engine control module of the driver's throttle requirement (pedal position). Both sensors are located in a single housing.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.

Indicated on display

Scheme 247

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Scheme 248

1. Press buttons -0-, -6- and -2- to select "Display Group 062" and confirm entry with -Q- button.

Note. The engine control module converts the voltage readings from the angle sensors into percentages of 5 V and displays them as percentages. (A signal wire voltage of 5 V is equivalent to 100%.)

Indicated on display

Scheme 249

1. Check specified display values for electronic throttle potentiometer voltages. DISPLAY GROUP 062: ELECTRONIC THROTTLE POTENTIOMETER VOLTAGES WITH IGNITION ON Display fields 1 2 3 4 Display Group 062: Electronic throttle potentiometer voltages with ignition on Display xx % xx % xx % xx % Indicates Throttle valve angle (angle sensor 1) Throttle valve angle (angle sensor 2) Accelerator position sensor 1 Accelerator position sensor 2 Work Range min.: 0% max.: 100% min.: 0% max.: 100% min.: 0% max.: 100% min.: 0% max.: 100% Specified value 3 to 93% 97 to 3% 12 to 92% 4 to 49%
2. Observe display fields 3 and 4.
3. Slowly depress accelerator to full throttle position. Percentage value in display field 3 should rise steadily, but without covering full tolerance range between 12 and 92%. Percentage value in display field 4 should also rise steadily but without covering full range of values (in this case 4 to 49%).

Note. The value shown in display field 3 should always be about twice as high as the value shown in display field 4.

If the display values do not appear as described

1. Check voltage supply and wiring to accelerator position senders. See «CHECKING VOLTAGE SUPPLY OF ACCELERATOR POSITION SENSORS»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-voltage-supply-of-accelerator-position) .
2. Adjust accelerator position sensors. See «ACCELERATOR PEDAL POSITION SENSOR, ADJUSTING»(/audi/a8/d3-2002-2005/remont/fuel-system/#fuel-supply-system-42l-v8-akb-aux-ays) .

Checking voltage supply of accelerator position sensors

1. Remove storage compartment on driver's side. See «STORAGE/COVERS»(/audi/a8/d3-2002-2005/remont/gauges-instrument-panels/#interior-equipment) .
2. Disconnect harness connector for accelerator position sensor.

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: ACCELERATOR POSITION SENSORS CIRCUIT TEST - VOLTAGE SUPPLY 6-pin connector on wiring harness, socket Specification 2 + Ground (GND) approx. 5 V 1 + 3 approx. 5 V 5 + Ground (GND) approx. 5 V 5 + 4 approx. 5 V

If the specifications are obtained

1. Check signal wiring. See «CHECKING SIGNAL WIRING AND WIRING CONNECTIONS BETWEEN ACCELERATOR POSITION SENSORS AND ENGINE CONTROL MODULE»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-signal-wiring-and-wiring-connections) .

If the specifications are not obtained

1. Check wiring between engine control module and accelerator position sensors. See «CHECKING SIGNAL WIRING AND WIRING CONNECTIONS BETWEEN ACCELERATOR POSITION SENSORS AND ENGINE CONTROL MODULE»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__checking-signal-wiring-and-wiring-connections) .

Checking signal wiring and wiring connections between accelerator position sensors and engine control module

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
2. Check for open circuit and short to B+ or Ground (GND) in following wiring connections: ACCELERATOR POSITION SENSORS CIRCUIT TEST - WIRING CONNECTION Connector socket VAG1598/31 test box Socket 1 (signal wire) 35 2 73 3 36 4 33 5 72 6 (signal wire) 34
3. Repair any open/short circuit as necessary.

If no wiring malfunction is detected

1. Replace accelerator position sensors. See «ACCELERATOR PEDAL POSITION SENSOR, REMOVING AND INSTALLING»(/audi/a8/d3-2002-2005/remont/fuel-system/#fuel-supply-system-42l-v8-akb-aux-ays) .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

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 throttled back for reasons of safety when the brakes are applied. To do this the control module requires signals from the brake light switch and also 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 un-required regulating processes.

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.

Indicated on display

Scheme 250

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Scheme 251

1. Press buttons -0-, -6- and -6- to select "Display Group 66" and confirm entry with -Q- button.

Indicated on display

Scheme 252

1. Observe display in display field 2. DISPLAY GROUP 066: SIGNALS TO ENGINE CONTROL MODULE WITH IGNITION ON Display fields 1 2 3 4 Display Group 066: Signals to engine control module with ignition on Display xxx km/h 1 0 0 0 xxx km/h 0 0 0 0 Indicates Actual speed Switch positions 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 «Relevance of figures in 4-digit readout in display field 2»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__relevance-of-figures-in-4-digit-readout)
2. Depress brake pedal

Relevance of figures in 4-digit readout in display field 2

RELEVANCE OF FIGURES IN 4-DIGIT READOUT IN DISPLAY FIELD 2

DISPLAY GROUP 066: SIGNALS TO ENGINE CONTROL MODULE

1. Allow brake pedal to return slowly to its normal position.
2. Both readouts should return from 1 to 0. If one or both of the displays does not change from 0 to 1
3. Test voltage supply. See «CHECKING WIRING CONNECTIONS»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .

Checking voltage supply

1. Remove storage compartment on driver's side. See «STORAGE/COVERS»(/audi/a8/d3-2002-2005/remont/gauges-instrument-panels/#interior-equipment) .
2. Disconnect 4-pin harness connector on brake pedal.
3. Connect hand-held multimeter (voltage range) between following sockets on connector
4. Switch ignition off. BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH CIRCUIT TEST - VOLTAGE CHECK (IGNITION OFF) 4-pin connector on wiring harness, socket Specification 1 + Ground (GND) Battery voltage
5. Switch ignition on. BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH CIRCUIT TEST - VOLTAGE CHECK (IGNITION ON) 4-pin connector on wiring harness, socket Specification 3 + Ground (GND) Battery voltage

If specifications are met

1. See «CHECKING WIRING CONNECTIONS»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays) .

If specifications are not met

1. Check wiring connections from sockets 1 and 3 of connector for open circuit or short to Ground (GND). See SYSTEM WIRING DIAGRAMS .
2. Repair any open/short circuit as necessary.

Checking wiring connections

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
2. Test following wiring connections for open circuits and short to B+ or Ground (GND): BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH CIRCUIT TEST - WIRING CONNECTION 4-pin connector on wiring harness, socket VAG1598/31 test box, socket 2 56 4 55 Resistance in wiring: max. 1.5 ohm See SYSTEM WIRING DIAGRAMS .
3. Repair any open/short circuit as necessary.

If no open circuit is identified in the wiring

1. Replace brake light switch/brake pedal switch.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Engine speed (RPM) signal, checking

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

To obtain engine speed, proceed as follows

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Ignition must be switched on.

Indicated on display

Scheme 253

1. Check all control modules for a missing RPM signal via "Automatic Test sequence."
2. Press -0- button twice to select "Automatic Test Sequence" function and confirm entry by pressing -Q- button.

No malfunctions relating to a "missing engine speed signal" should be stored in any of the control modules.

If one of the control modules indicates a malfunction

1. Check for open circuit or short circuit between engine control module and control module concerned. See SYSTEM WIRING DIAGRAMS .
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

A/C compressor shut-off, checking

Note. The A/C 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 A/C compressor. The engine control module will shut off the A/C compressor in the following circumstances: - In emergency running mode (back-up) - When a signal is received from the Transmission Control Module (TCM) (kickdown switch) - When the function "Basic Setting" function is initiated (function 04)

1. Climate control functioning properly
2. No malfunctions recorded in DTC memory of engine control module
3. Interior temperature greater than +15 °C

1. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be idling.

Indicated on display

Scheme 254

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Scheme 255

1. Press buttons -0-, -5- and -0- to select "Display Group 050" and confirm entry with -Q- button.

Indicated on display

Scheme 256

1. Check A/C compressor shut-off (display field 4). DISPLAY GROUP 050: SIGNALS TO ENGINE CONTROL MODULE (1 OF 2) Display fields 1 2 3 4 Display Group 050: Signals to engine control module Display xxx rpm xxx rpm A/C-Low Compr. OFF Indicates Actual engine speed (true value) Specified engine speed (theoretical value) Air conditioner requirement A/C compressor status Work range A/C-Low A/C -High Compr. OFF Compr. ON Specified value A/C-Low Compr. OFF
2. Switch on A/C by pressing "Auto" button. Compressor should run (display field 4).
3. Set A/C to maximum hot/cold air output (display field 3). DISPLAY GROUP 50: SIGNALS TO ENGINE CONTROL MODULE (2 OF 2) Display fields 1 2 3 4 Display Group 50: Signals to engine control module Display xxx rpm xxx rpm A/C-High Compr. ON Indicates Actual engine speed (true value) Specified engine speed (theoretical value) Air conditioner requirement A/C compressor status Range A/C-Low A/C-High Compr. OFF Compr. ON Specified value A/C-High Compr. ON
4. Switch off compressor with controls on A/C control head. Specification for display field 4: Display should change from "Compr.ON" to "Compr.OFF."

If the readout in display field 4 is not as described

1. Switch ignition off.
2. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
3. Test following wiring connections for open circuit and/or short to B+ or Ground (GND). A/C COMPRESSOR SHUT-OFF CIRCUIT TEST - OPEN CIRCUIT AND/OR SHORT TO GROUND VAG1598/31 test box, socket Air conditioner, contact 41 See SYSTEM WIRING DIAGRAMS .

Resistance in wiring: max. 1.5 ohm

1. Repair any open/short circuit as necessary.
2. If no malfunctions are identified in wiring, check function of climate control. See «AUTOMATIC CLIMATE CONTROL SYSTEM, ON BOARD DIAGNOSTIC (OBD)»(/audi/a8/d3-2002-2005/remont/heated-glassdefoggers/#on-board-diagnostic-obd-hvac-can-defrosters) .
3. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Crash signal, checking

If an accident occurred which lead to the activation of the seat belt tensioner/airbag, the engine control module shuts off the activation of fuel pump relay. Therefore, excessive fuel delivery is prevented is case the fuel system is damaged.

As long as the malfunction "Crash shut-down activated" is stored or not erased in the engine control module, the fuel pump will not prime the system (pre -run) when the ignition key is turned on and the fuel system will not be pressurized. Therefore, it is possible that the engine starts with a delay.

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .

Test the following wiring connections for open circuit and/or short to B+ or Ground (GND) and open circuit.

CRASH SIGNAL CIRCUIT TEST - OPEN CIRCUIT AND/OR SHORT TO GROUND

Resistance in wiring: max. 1.5 ohm

Eliminate open circuit or short circuit.

See SYSTEM WIRING DIAGRAMS .

If no malfunctions are found in wiring: Check DTC memory of airbag control module.

1. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . Readiness code must be generated if DTC memory was erased. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Engine mounts, checking

The electro-hydraulic engine mounts with electrical activation prevent engine vibration to the body over the entire RPM range.

At idle the engine mounts are soft.

In driving mode the engine mounts are hard.

1. Switch ignition on.
2. Perform output Diagnostic Test Mode (DTM) for left and right engine mounts. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) .

Indicated on display

Scheme 257

1. Press -->button.

Indicated on display

Scheme 258

During activation of the engine mounts both solenoids valve must click audible.

If the specified values are not obtained, perform the following checks

Scheme 259

1. Disconnect harness connector of particular solenoid valve.
2. Connect VAG1527B diode test lamp with test leads from VAG1594 connector test kit on socket 1 of connector (B+) and engine Ground (GND).
3. Activate starter for a few seconds. Engine can also start. Diode test lamp must light up.

If the diode test lamp does not light up, perform the following checks.

1. Check fuse for engine mounts. See SYSTEM WIRING DIAGRAMS .

If the fuse is OK

Scheme 260

1. Check wiring connection from socket 1 via fuse to fuel pump relay for continuity. See SYSTEM WIRING DIAGRAMS .

Scheme 261

1. Disconnect harness connector of particular solenoid valve.
2. Connect VAG1527B diode test lamp with test leads from VAG1594 connector test kit on socket 1 of connector (B+) and engine Ground (GND).
3. Perform output Diagnostic Test Mode (DTM) and activate particular engine mount. See «OUTPUT DIAGNOSTIC TEST MODE (DTM) (FUNCTION 03) (ENGINE CODES AUX, AKB)»(ref-216437-S12154373892006020800000) . Diode test lamp must blink during activation of engine mounts.

If the diode test lamp blinks continuously.

Scheme 262

1. Check wiring connection from socket 2 of particular connector of engine mount for short to Ground.

If diode test lamp does not blink.

Scheme 263

1. Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself. See «WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX»(/audi/a8/d3-2002-2005/remont/fuel-system/#multiport-fuel-injection-mfi-42l-v8-akb-aux-ays__wiring-and-component-check-with-vag159831) .
2. Check wiring connection of particular connector of engine mount for open circuit and short circuit to B+. ENGINE MOUNT CIRCUIT TEST - OPEN CIRCUIT AND SHORT CIRCUIT TO B+ 2-pin harness connector, terminal VAG1598/31 test box, socket 2 105 2 116 Wiring resistance: max. 1.5 ohm See SYSTEM WIRING DIAGRAMS .
3. Eliminate short or open circuit if necessary.

If there is no malfunction in the wiring

1. Replace particular engine mount.
2. Display readiness code. See «READINESS CODE, CHECKING»(ref-216437-S40758807032006020800000) . If DTC memory was erased generate readiness code. See «READINESS CODE, GENERATING»(ref-216437-S25676712792006020800000) .

Data exchange between Engine Control Module (ECM), ABS/EDL control module, Transmission Control Module (TCM) or instrument cluster, checking

Note. The data exchange between the various control modules is carried out via a data bus. The term "CAN data bus" refers to a system for transmitting and distributing data. The wires which connect the control modules and convey the data between them are called data wires. Data is transmitted via data wires in serial, i.e. in a specific order to the connected control modules (e.g. engine rpm and accelerator pedal position).

Checking bus system

The DTC table indicates that the data exchange between the engine control module, ABS control module and transmission control module or instrument cluster should be tested.

1. Make sure that multi-pin connectors for control modules are properly connected
2. Connect vehicle diagnostic, testing and information system VAS 5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". See «VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051 OR VAG1551, CONNECTING AND SELECTING FUNCTIONS»(ref-216437-S40962647232006020800000) . Engine must be at idle.

Indicated on display

Scheme 264

1. Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Scheme 265

1. Press buttons -1-, -2- and -5- to select "Display Group 125" and confirm entry with -Q- button.

Indicated on display

Scheme 266

DISPLAY GROUP 125: CAN DATA BUS MESSAGES

Automatic Test Sequence

1. Press button -0- twice for address word "Automatic Test Sequence" and confirm entry with -Q- button. VAG1551 scan tool transmits all known address words one after another.

When a control module answers with its identification the number of stored malfunctions appears on the display or "No DTC recognized."

Any system malfunctions that are stored will be displayed one after the other and printed out. The VAG1551 scan tool will then transmit the next address word.

Scheme 267

The automatic test sequence has ended when the following appears on the display

If malfunctions have been stored relating to the "Data bus drive" or to data transmission: "No message from...."

1. Check Part No. and coding to make sure that vehicle is equipped with correct ECM, TCM, ABS control module, instrument cluster and AICC control module (if equipped).

If the correct control modules are installed, test the CAN data bus system.

Checking two-wire bus system

Three or more control modules communicating via a "two-wire bus system"

1. Read out malfunctions stored in control modules.

This will help to trace a malfunction in the wiring.

Example 1

Scheme 268

From the malfunctions present in the DTC memories, notice that control module 1 has no connection to control modules 2 or 3.

CONTROL MODULE DTC PROBLEM DIAGNOSTIC (EXAMPLE 1)

1. Switch ignition off.
2. Disconnect control modules which are linked by bus wires and check whether there is an open circuit in one bus wire. See SYSTEM WIRING DIAGRAMS .
3. If no malfunction can be identified in bus wires replace control module 1.

Example 2

From the malfunctions present in the DTC memories, notice that control module 2 has no connection to control modules 1 or 3.

Scheme 269

CONTROL MODULE DTC PROBLEM DIAGNOSTIC (EXAMPLE 2)

1. Switch ignition off.
2. Disconnect control modules which are linked by bus wires and check whether there is an open circuit in one bus wire. See SYSTEM WIRING DIAGRAMS .
3. If no malfunction can be identified in bus wires replace control module 2.

Example 3

From the malfunctions present in the DTC memories, notice that none of the control modules are able to transmit or receive signals.

CONTROL MODULE DTC PROBLEM DIAGNOSTIC (EXAMPLE 3)

Scheme 270

Scheme 271

1. Switch ignition off.
2. Disconnect control modules which are linked by bus wires and check for a short circuit between bus wires. See SYSTEM WIRING DIAGRAMS .
3. Check bus wires for short to B+ and short to Ground (GND).

If the cause of the malfunction "Data Bus Powertrain Malfunction" cannot be found in the data bus wires, check whether one of the control modules is causing the malfunction

At this stage all the control modules which communicate via the CAN data bus are disconnected. The ignition is switched off.

1. Connect one control module.
2. Connect VAG1551 scan tool. Switch ignition on and erase DTC memory of control module which has just been connected. End output from scan tool with function 06 "End Output."
3. Switch ignition off and then on again.
4. Leave ignition switched on for 10 seconds. Then check DTC memory of control module that has just been connected, using scan tool.
5. If malfunction "Data Bus Powertrain Malfunction" is now indicated, replace control module which has just been connected.
6. If malfunction "Data Bus Powertrain Malfunction" is not indicated, connect next control module, and repeat above procedure.

See also:
• ANTI-THEFT IMMOBILIZER, ON BOARD DIAGNOSTIC
• FUEL SUPPLY SYSTEM
• STORAGE/COVERS
• AUTOMATIC CLIMATE CONTROL SYSTEM, ON BOARD DIAGNOSTIC (OBD)
• ELECTRONIC ENGINE POWER CONTROL (EPC) WARNING LIGHT, CHECKING
• MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITH METAL ANTI -THEFT HOUSING), REPLACING
• THROTTLE VALVE CONTROL MODULE, ADAPTATION
• ACTIVATING CRUISE CONTROL SYSTEM (CCS)
• WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX
• If the idle speed is too high or too low, or if the engine does not idle smoothly, and there are no malfunctions stored in the DTC memory, perform the following tests (marked with dots)
• Relevance of figures in 5-digit readout in Display Group 056
• CHECKING OXYGEN SENSOR ADAPTATION AND OXYGEN SENSOR CONTROL
• CHECKING VOLTAGE SUPPLY
• CHECKING WIRING CONNECTIONS
• TESTING ACTIVATION OF FUEL PUMP RELAY
• READING DISPLAY GROUP 002
• CHECKING WIRING FOR MAF SENSOR
• COMPONENT LOCATIONS, OVERVIEW
• SIGNIFICANCE OF 3 DIGIT INDICATION IN DISPLAY GROUP 30
• OXYGEN SENSOR SIGNAL WIRE AND ACTIVATION, CHECKING
• EVALUATION DISPLAY GROUP 33
• EVALUATION DISPLAY GROUP 32
• OXYGEN SENSOR HEATER FOR OXYGEN SENSOR, CHECKING
• CHECKING OXYGEN SENSOR WIRING FOR HEATED OXYGEN SENSOR (HO2S) -G39
• CHECKING WIRING FOR OXYGEN SENSOR (O2S) BEHIND THREE WAY CATALYTIC CONVERTER (TWC) -G130
• CONTINUATION
• EVALUATION DISPLAY GROUP 037 AND 038
• CHECKING VOLTAGE SUPPLY FOR OXYGEN SENSOR HEATER
• CHECKING WIRING FOR HEATED OXYGEN SENSOR (HO2S) 2 -G108
• INTAKE MANIFOLD CHANGE -OVER VALVE -N156- AND INTAKE MANIFOLD TUNING (IMT) VALVE -2- -N261-, CHECKING
• CHECKING VOLTAGE SUPPLY TO INTAKE MANIFOLD CHANGE-OVER VALVE
• CHECKING ACTIVATION OF INTAKE MANIFOLD CHANGE-OVER VALVE
• INTAKE MANIFOLD CHANGE-OVER, CHECKING (A8 VEHICLES)
• CHECKING VACUUM SYSTEM FOR LEAKS
• CHECKING POWER SUPPLY TO SOLENOID VALVE
• FUEL PUMP (FP) RELAY -J17- AND RELAY ACTIVATION, CHECKING
• CHECK ACTIVATION OF SECONDARY AIR INJECTION PUMP RELAY
• Throttle valve control module, adaptation notes
• TEST CONDITIONS FOR ADAPTATION OF THROTTLE VALVE CONTROL MODULE
• CHECKING VOLTAGE SUPPLY OF ACCELERATOR POSITION SENSORS
• CHECKING SIGNAL WIRING AND WIRING CONNECTIONS BETWEEN ACCELERATOR POSITION SENSORS AND ENGINE CONTROL MODULE
• Relevance of figures in 4-digit readout in display field 2