Exhaust System, Emission Control, Generic Scan Tool (2.8l v6 Aha, Atq) Audi A6 C5

Exhaust system components, removing and installing

Note. After exhaust system repairs, make sure exhaust system is not under stress and that it has sufficient clearance from the bodywork. If necessary, loosen double clamps and align exhaust pipe so that sufficient clearance is maintained to the bodywork and mounts carry uniform loads. Do not use any silicone sealant. Traces of silicone components which are sucked into the engine are not burned there, and they damage the oxygen sensor. Always replace self-locking nuts. Components marked with * are tested via On Board Diagnostic (OBD). See DIAGNOSTIC MODE 3: CHECK DTC MEMORY .

1. Check catalytic converter. See «THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq)

Exhaust manifold, front exhaust pipe with Three Way Catalytic Converter (TWC) and attachments

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

Note. The following list refers to items in (Scheme 7).

1. Heated Oxygen Sensor (HO2S) - G39- bank 1*, 50 Nm Use "G5" to grease thread only; do not let "G5" get onto slits of oxygen sensor body Check oxygen sensor heater for Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC). See «COMPONENTS, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) . Check Oxygen Sensor (O2S) and oxygen sensor control before Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR (O2S) AND OXYGEN SENSOR CONTROL BEFORE THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-o2s-and-oxygen-sensor) .
2. 4-pin harness connector Black for Heated Oxygen Sensor (HO2S) -G39- before catalytic converter and Oxygen Sensor (O2S) Heater -Z19-, cylinder bank 1 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview) .
3. Right-front exhaust pipe with Three Way Catalytic Converter (TWC) Check catalytic converter. See «THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) .
4. Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- bank 1*, 50 Nm Only use "G 052 112 A3" to grease thread; do not let "G 052 112 A3" get onto slit of oxygen sensor Check oxygen sensor heater for Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR HEATER FOR OXYGEN SENSORS BEFORE THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-heater-for-oxygen-sensors) . Check Oxygen Sensor (O2S) and oxygen sensor control behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR AND OXYGEN SENSOR CONTROL BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-and-oxygen-sensor-control) .
5. 4-pin harness connector green for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S) Heater 1 (behind Three Way Catalytic Converter (TWC)) - Z29-, cylinder bank 1 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
6. 25 Nm
7. Spacer sleeve
8. Bracket
9. Spring
10. Bolt
11. Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- bank 2*, 50 Nm Only use "G 052 112 A3" to grease thread; do not let "G 052 112 A3" get onto slit of oxygen sensor Check oxygen sensor heater for Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR HEATER FOR OXYGEN SENSORS BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-heater-for-oxygen-sensors) . Check Oxygen Sensor (O2S) and oxygen sensor control behind Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR AND OXYGEN SENSOR CONTROL BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-and-oxygen-sensor-control) .
12. 4-pin harness connector brown for Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- and Oxygen Sensor (O2S) Heater 2 (behind Three Way Catalytic Converter (TWC)) - Z30-, cylinder bank 2 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
13. To front and center muffler All Wheel Drive (AWD) vehicles See «MUFFLERS WITH MOUNTS»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) , item no. 7 Front Wheel Drive (FWD) vehicles See , item 13
14. Left-front exhaust pipe with Three Way Catalytic Converter (TWC) Check catalytic converter. See «THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) .
15. Heated Oxygen Sensor (HO2S) 2 - G108-* bank 2, 50 Nm Only use "G 052 112 A3" to grease thread; do not let "G 052 112 A3" get onto slit of oxygen sensor Check oxygen sensor heater for Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC). See «COMPONENTS, CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq) . Check Oxygen Sensor (O2S) and oxygen sensor control before Three Way Catalytic Converter (TWC). See «OXYGEN SENSOR (O2S) AND OXYGEN SENSOR CONTROL BEFORE THREE WAY CATALYTIC CONVERTER (TWC), CHECKING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__oxygen-sensor-o2s-and-oxygen-sensor) .
16. 4-pin harness connector Black for Heated Oxygen Sensor (HO2S) 2 -G108- and Oxygen Sensor (O2S) 2 Heater 2 -Z28-, cylinder bank 2 Component location, see «COMPONENT LOCATIONS, OVERVIEW»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__component-locations-overview)
17. Upper heat shield
18. Lower heat shield
19. Left-side exhaust manifold
20. Right-side exhaust manifold
21. Gasket Always replace

Exploded View Of Exhaust System. Scheme 7

All Wheel Drive (AWD) vehicles

Front Wheel Drive (FWD) vehicles FRONT WHEEL DRIVE (FWD) VEHICLES .

Note. The following list refers to items in (Scheme 8).

1. 40 Nm
2. From Three Way Catalytic Converter (TWC)
3. Carriage bolts
4. Double clamp
5. 25 Nm
6. Suspended mount With retainer ring
7. Center muffler
8. Double clamp (for repair)
9. Separating point At factory, center and rear mufflers are installed as a single component. Replacement center and rear mufflers are supplied separately, with double clamp for connecting joint. Using VAG1523 body repair saw, cut connecting pipe at separating point (arrow) at right angle. (Scheme 8)
10. Right rear muffler
11. Suspended mount
12. Bracket
13. Left rear muffler

Exploded View Of Mufflers With Mounts (AWD Vehicles). Scheme 8

Recommended special tools and equipment

1. Body saw (e.g. VAG1523 body repair saw)

Procedure

1. Separate connecting pipe between center muffler and rear muffler at the location marked with a groove

Separating Point Between Center And Rear Muffler (AWD Vehicles). Scheme 9

Dimension -a- approx. 244 mm.

Front Wheel Drive (FWD) vehicles

Note. The following list refers to items in (Scheme 10).

1. 40 Nm
2. From Three Way Catalytic Converter (TWC)
3. Carriage bolts
4. Double clamp
5. 25 Nm
6. Suspended mount With retainer ring
7. Center muffler
8. Bracket
9. Suspended mount
10. Rear muffler
11. Double clamp (for repair)
12. Separating point At factory, center and rear mufflers are installed as a single component. Replacement center and rear mufflers are supplied separately, with double clamp for connecting joint. Using VAG1523 body repair saw, cut connecting pipe at separating point (arrow) at right angle. See «SEPARATING POINT BETWEEN CENTER AND REAR MUFFLER»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) .
13. Front muffler

Exploded View Of Front Wheel Drive (FWD) Vehicle Exhaust. Scheme 10

Separating Point Between Center And Rear Muffler

Recommended special tools and equipment

1. Body saw (e.g. VAG1523 body repair saw)

Procedure

1. Separate connecting pipe between center muffler and rear muffler at the location marked with a groove: Dimension -a- approx. 182 mm.

Separating Point Between Center And Rear Muffler (FWD Vehicles). Scheme 11

Function test

1. Select the measuring value "Test-ID 01: Catalytic converter" and check whether the specified values are being reached. See «DIAGNOSTIC MODE 6: CHECK TEST RESULTS OF COMPONENTS THAT ARE NOT CONTINUOUSLY MONITORED»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

Secondary Air Injection (AIR) system

Function

Air is blown behind the exhaust valves by the Secondary Air Injection (AIR) system during a cold start. This adds oxygen to the exhaust, initiating a secondary combustion and thereby shortening the warm-up phase of the catalytic converter. Activation occurs from Motronic Engine Control Module (ECM) -J220- via Secondary Air Injection (AIR) Pump Relay -J299- to Secondary Air Injection (AIR) Solenoid Valve -N112 - to the combination valve.

Check secondary air system for proper seal. See SECONDARY AIR SYSTEM, CHECKING FOR PROPER SEAL .

Note. Components marked with * are tested via On Board Diagnostic (OBD). See DIAGNOSTIC MODE 3: CHECK DTC MEMORY. Secondary Air Injection (AIR) Pump Relay -J299-* (Scheme 14)

Secondary Air Injection (AIR) Pump Motor -V101- Assembly overview

Note. The following list refers to items in (Scheme 12).

1. Secondary Air Injection (AIR) Pump Motor -V101-* Checking, see «SECONDARY AIR INJECTION (AIR) PUMP MOTOR, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq)
2. Front right longmember
3. 10 Nm
4. Bracket For Secondary Air Injection (AIR) pump motor Secured at intake manifold
5. Damping ring Securing collar must point to the eye of the pump
6. Protective ring
7. Connector black, 2 -pin For Secondary Air Injection (AIR) pump motor
8. to connecting pipe See item 15
9. Pressure hose Check for secure fitting To disengage, squeeze together at front
10. O-ring Always replace
11. Intake hose Check for secure fitting To disengage, squeeze together at front
12. from upper air filter housing See «AIR FILTER, DISASSEMBLING AND ASSEMBLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__air-filter-disassembling-and-assembling) , item no. 5.

Exploded View Of Secondary Air Injection (AIR) System. Scheme 12

Connecting pipe and combination valves - Assembly overview

Note. The following list refers to items in (Scheme 13).

1. Combination valve, right Checking, see «COMBINATION VALVES, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) Removing and installing, see «COMBINATION VALVES, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__combination-valves-removing-and-installing)
2. Gasket Always replace
3. 10 Nm
4. 25 Nm
5. Y-piece
6. Secondary Air Injection (AIR) Solenoid Valve -N112 -* Checking, see «SECONDARY AIR INJECTION (AIR) VALVE, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__secondary-air-injection-air-valve-checking)
7. 6 Nm
8. from Y -piece See «THROTTLE VALVE CONTROL MODULE, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__throttle-valve-control-module-removing-and) , item no. 8.
9. Combination valve, left Checking, see «COMBINATION VALVES, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) Removing and installing, see «COMBINATION VALVES, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__combination-valves-removing-and-installing)
10. Gasket Always replace
11. Connecting piece
12. Gasket Always replace
13. Pressure hose Check for secure fitting To disengage, squeeze together at front
14. O-ring Always replace
15. Connection tube
16. Connecting piece

Exploded View Of Secondary Air Injection Connecting Pipes And Combination Valves. Scheme 13

Secondary Air Injection (AIR) Pump Relay -J299-* (-1-) with fuse -2- in protective housing (engine compartment, left)

Note. Remove battery Ground (GND) strap if tools are necessary for removal of relays or control modules from the relay carrier. Obtain radio code for radios with anti -theft coding before disconnecting battery. Check activation of the Secondary Air Injection (AIR) Pump Relay

Identifying Secondary Air Injection (AIR) Pump Relay Location. Scheme 14

1. Select the measuring value "Test-ID 03: Secondary Air Injection (AIR) system" and check whether the specified values are being reached. See «DIAGNOSTIC MODE 6: CHECK TEST RESULTS OF COMPONENTS THAT ARE NOT CONTINUOUSLY MONITORED»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
2. Check specified values at idle.

TEST-ID 03: SECONDARY AIR INJECTION (AIR) SYSTEM

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

1. End diagnosis and switch ignition off.

If the specified values are not reached, go to CHECKING PROPER SEAL .

Checking Proper Seal

1. Check the connecting lines and hoses between Secondary Air Injection (AIR) Pump Motor and combination valves for proper seal. See «SECONDARY AIR INJECTION (AIR) SYSTEM COMPONENTS, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) .
2. Repeat function test.
3. Check hoses and hose connections for secure seating.
4. Repeat function test.

If malfunction is no longer present

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

Secondary Air Injection (AIR) valve, checking

Solenoid valve is closed when no voltage is present.

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

Scheme 15

1. The respective fuses of Secondary Air Injection (AIR) Solenoid Valve -N112- must be OK: (Scheme 15): Identifying Fuses In Fuse Holder
2. Ignition switched off.

Scheme 16

Scheme 17

1. Disconnect 2-pin connector -1- from Secondary Air Injection (AIR) Solenoid Valve -N112- (-2-). (Scheme 16): Disconnecting Pin Connector From Secondary Air Injection (AIR) Solenoid Valve
2. Measure resistance between terminals of solenoid valve. Specified value: 25.0 to 35.0 ohm (Scheme 17): Measuring Resistance Between Terminals Of Secondary Air Injection (AIR) Solenoid Valve

If specified value is not obtained

1. Replace Secondary Air Injection (AIR) Solenoid Valve -N112-. See «CONNECTING PIPE AND COMBINATION VALVES - ASSEMBLY OVERVIEW»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__connecting-pipe-and-combination-valves) , item 6.
2. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
3. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If specified value is obtained

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

Vehicles with engine code AHA

1. Check wire between test box socket 33 + 2-pin connector terminal 2 for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

Identifying Secondary Air Injection (AIR) Solenoid Valve Harness Connector Terminals. Scheme 18

Vehicles with engine code ATQ

1. Check wire between test box socket 44+2-pin connector terminal 2 for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm

Identifying Secondary Air Injection (AIR) Solenoid Valve Harness Connector Terminals. Scheme 19

Continuation for all vehicles

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

If no malfunctions are found in wires

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

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

Scheme 20

1. The respective fuses of Secondary Air Injection (AIR) Pump Motor -V101- must be OK: (Scheme 20): Identifying Fuse Holder
2. Fuel Pump (FP) Relay -J17- must be OK, check
3. Secondary Air Injection (AIR) Pump Relay -J299- must be OK, check
4. Battery voltage must be at least 11.5 volts.
5. All electrical consumers like, for example, lights and rear window heating must be switched off.
6. Ignition switched off.

Scheme 21

1. Remove front noise insulation. (Scheme 21): Disconnecting Pin Connector From Secondary Air Injection (AIR) Pump Motor
2. Disconnect 2-pin connector -1- from Secondary Air Injection (AIR) Pump Motor -V101- -2-.
3. Disconnect pressure hose (arrow) between Secondary Air Injection (AIR) Pump Motor -V101- and connecting line.

Note. To disengage, compress the buttons at the hose coupling.

Scheme 22

1. Connect Secondary Air Injection (AIR) Pump Motor to the B+ and Ground (GND) terminals of the battery using the respective adapter cables. (Scheme 22): Connecting Secondary Air Injection (AIR) Pump Motor To B+ And Ground (GND) Terminals Of Battery The Secondary Air Injection (AIR) Pump Motor must start up and air must escape at compressed-air connection (arrow).

If the motor does not start up, or no air or only very little air escapes

1. Disconnect connection between Secondary Air Injection (AIR) Pump Motor and battery.
2. Replace Secondary Air Injection (AIR) Pump Motor -V101-. See «SECONDARY AIR INJECTION (AIR) SYSTEM COMPONENTS, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq) .
3. Erase DTC memory of Engine Control Module (ECM). See «DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .
4. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-generic-scan-tool-28l-v6-aha-atq) .

If motor starts, and air escapes

Scheme 23

Scheme 24

Scheme 25

1. Disconnect connection between Secondary Air Injection (AIR) Pump Motor and battery. (Scheme 23): Pulling Off Rubber Seal Of Plenum Chamber Cover
2. Pull off rubber seal of plenum chamber cover in direction of.
3. Remove cover -1- toward front.
4. Remove securing screws at cover of protective housing for control modules -arrows- and remove cover. (Scheme 24): Removing Securing Screws At Cover Of Protective Housing For Control Modules
5. Remove Secondary Air Injection (AIR) pump relay (arrow) from relay carrier in protective housing for control modules. (Scheme 25): Removing Secondary Air Injection (AIR) Pump Relay

Note. Remove battery Ground (GND) strap if tools are necessary for removal of relays or control modules from the relay carrier. Obtain radio code for radios with anti -theft coding before disconnecting battery.

Scheme 26

Scheme 27

1. Check wire between terminal 2 of relay carrier (arrow) and terminal 2 of 2-pin connector of Secondary Air Injection (AIR) Pump Motor for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm (Scheme 26): Identifying Secondary Air Injection (AIR) Pump Relay Terminals In Relay Carrier
2. Also check the wire for short circuit to B+ and Ground (GND). Specified value: INFINITY ohm
3. Check wire between 2-pin connector terminal 1 and Ground (GND) for open circuit according to wiring diagram. Wire resistance: max: 1.5 ohm (Scheme 27): Identifying Secondary Air Injection (AIR) Pump Harness Connector Terminals

If no malfunctions are found in wires

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

1. VAG1390 Hand Vacuum Pump

Test requirements

1. No leaks in vacuum lines or hose connections.
2. Vacuum hoses not clogged or kinked
3. Pressure hose for Secondary Air Injection (AIR) Pump Motor not clogged or kinked

Scheme 28

Scheme 29

1. Disconnect vacuum hose of the combination valve to be checked at Y-piece (arrow). (Scheme 28): Disconnecting Vacuum Hose Of Combination Valve
2. Connect VAG1390 hand vacuum pump to vacuum hose of the valve to be checked. (Scheme 29): Connecting VAG1390 Hand Vacuum Pump To Vacuum Hose Of Valve

Note. Do not use pressurized air for the following test!

Scheme 30

1. Remove front noise insulation.
2. Disconnect pressure hose (arrow) between Secondary Air Injection (AIR) Pump Motor and connecting line and blow into it with light pressure. (Scheme 30): Disconnecting Pressure Hose Both combination valves must be closed.

Note. To disengage, compress the buttons at the hose coupling.

1. Operate hand vacuum pump. The respective combination valve must open.

If the combination valve does not open or it is constantly open

1. Replace the respective combination valve. See «COMBINATION VALVES, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-control-generic-scan-tool-28l-v6-aha-atq__combination-valves-removing-and-installing) .

Combination valves, removing and installing

Note. Always replace all seals and sealing rings.

Scheme 31

1. Unbolt engine coolant reservoir and lay aside.
2. Disconnect vacuum hose -1- from combination valve. (Scheme 31) (Scheme 31): Removing Left Combination Valve
3. Remove securing bolts -2- and remove connecting line.
4. Remove securing bolts -3- and remove combination valve from cylinder head.

Installing

Installation is performed in the reverse order of removal.

Scheme 32

1. Remove connection hose between air filter and intake air scoop. See «FUEL INJECTION SYSTEM, REMOVING AND INSTALLING PARTS»(/audi/a6/c5-1997-2001/remont/fuel-system/#multiport-fuel-injection-mfi-generic-scan-tool-28l-v6-aha-atq__fuel-injection-system-removing-and-installing), item 5.
2. Remove intake air scoop from Throttle Valve Control Module. (Scheme 32): Removing Right Combination Valve
3. Disconnect vacuum hose -1- from combination valve. (Scheme 32)
4. Remove securing bolts -2- and remove connecting line.
5. Remove securing bolts -3- and remove combination valve from cylinder head.
6. If necessary, remove securing bolts -4- for connecting line bracket.

Installation is performed in the reverse order of removal.

See also:
• DIAGNOSTIC MODE 3: CHECK DTC MEMORY
• COMPONENTS, CHECKING
• OXYGEN SENSOR (O2S) AND OXYGEN SENSOR CONTROL BEFORE THREE WAY CATALYTIC CONVERTER (TWC), CHECKING
• COMPONENT LOCATIONS, OVERVIEW
• OXYGEN SENSOR HEATER FOR OXYGEN SENSORS BEFORE THREE WAY CATALYTIC CONVERTER (TWC), CHECKING
• OXYGEN SENSOR AND OXYGEN SENSOR CONTROL BEHIND THREE WAY CATALYTIC CONVERTER (TWC), CHECKING
• AIR FILTER, DISASSEMBLING AND ASSEMBLING
• THROTTLE VALVE CONTROL MODULE, REMOVING AND INSTALLING
• ENGINE CONTROL MODULE (ECM), REPLACING
• FUEL INJECTION SYSTEM, REMOVING AND INSTALLING PARTS
• THREE WAY CATALYTIC CONVERTER (TWC), CHECKING
• FRONT WHEEL DRIVE (FWD) VEHICLES
• COMBINATION VALVES, REMOVING AND INSTALLING
• SECONDARY AIR INJECTION (AIR) VALVE, CHECKING
• CHECKING PROPER SEAL
• CONNECTING PIPE AND COMBINATION VALVES - ASSEMBLY OVERVIEW