Exhaust System, Emission Controls (2.8l v6 Aha, Atq)

Exhaust system components, removing and installing

WARNING

Do not re-use any fasteners that are worn or deformed in normal use. Some fasteners are designed to be used only once, and are unreliable and may fail if used a second time. This includes, but is not limited to, nuts, bolts, washers, circlips and cotter pins. Always follow the recommendations in this manual-replace these fasteners with new parts where indicated, and any other time it is deemed necessary by inspection.

Note. After servicing the exhaust system, make sure that the system is not under stress and that there is sufficient clearance from the bodywork. If necessary, loosen the double clamps and align the muffler and exhaust pipe so that there is sufficient clearance to the bodywork. The retaining rings should also be evenly loaded. Always replace self-locking nuts.

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

The following list pertains to (Scheme 1).

Spacer sleeve
Bolt
Washers
Bracket
Spacer bushing
Rubber bushing
25 Nm (18 ft lb)
Spring
Bolt 25 Nm (18 ft lb)
To center muffler
Left-front exhaust pipe with Three Way Catalytic Converter (TWC)
Heated Oxygen Sensor (HO2S) 2 -G108- 50 Nm (37 ft lb) Only grease threads using "G5" ("G5" must not get into slots on body of sensor) CAUTION: Part numbers are listed here for reference only. Always check with your Parts department for the latest information. Checking DTC memory: See «CHECK DTC MEMORY (SCAN TOOL FUNCTION 02)»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-28l-v6-aha) Checking components & checking heating function: See «MOTRONIC MULTIPORT FUEL INJECTION (MFI) AND IGNITION SYSTEM»(ref-216409-S37200151692006012100000)
4-pin harness connectors Black Mounted to bulkhead For Heated Oxygen Sensors (HO2S) and for heating function
25 Nm (18 ft lb)
Cover cap 10 Nm (7 ft lb)
Connection
Upper heat shield
Lower heat shield
Left-side exhaust manifold
Gaskets Always replace
Right-side exhaust manifold
Heated Oxygen Sensor (HO2S) -G39- 50 Nm (37 ft lb) Only grease threads with "G5" ("G5" must not get into slots on body of sensor) CAUTION: Part numbers are listed here for reference only. Always check with your Parts department for the latest information. Checking DTC memory: See «CHECK DTC MEMORY (SCAN TOOL FUNCTION 02)»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-28l-v6-aha) Checking components & checking heating function: See «MOTRONIC MULTIPORT FUEL INJECTION (MFI) AND IGNITION SYSTEM»(ref-216409-S37200151692006012100000)
Right-front exhaust pipe with Three Way Catalytic Converter (TWC)

Vehicles with all-wheel drive

Vehicles with front-wheel drive , see VEHICLES WITH FRONT-WHEEL DRIVE

The following list pertains to (Scheme 2).

40 Nm (30 ft lb)
From Three Way Catalytic Converter (TWC)
Carriage bolts
Double clamp
25 Nm (18 ft lb)
Mounts With retaining ring
Center muffler
Double clamp (for repair)
Separating points At factory, center and rear mufflers are installed as single component. Replacement center and rear mufflers are supplied separately, with double clamp for connecting joint Cutting through at separating point, see «SEPARATING POINT BETWEEN CENTER MUFFLER AND REAR MUFFLER»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-controls-28l-v6-aha-atq)
Right-rear muffler
Mounts
Brackets
Left-rear muffler

Cutting

Using VAG1523 body saw, cut through connecting pipe between center muffler and rear muffler at groove. Distance -a-: approx. 244 mm (9-1/2 in.).

Vehicles with front-wheel drive

The following list pertains to see scheme 4.

40 Nm (30 ft lb)
From Three Way Catalytic Converter (TWC)
Carriage bolts
Double clamps
25 Nm (18 ft lb)
Mounts With retaining ring
Center muffler
Bracket
Mount
Rear muffler
Double clamp (for repair)
Separating point At factory, center and rear mufflers are installed as single component. Replacement center and rear mufflers are supplied separately, with double clamp for connecting joint Cutting through at separating point, see «SEPARATING POINT BETWEEN CENTER MUFFLER AND REAR MUFFLER»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-controls-28l-v6-aha-atq)
To front mufflers

Using VAG1523 body saw, cut through connecting pipe between center muffler and rear muffler at groove. Distance -a-: approx. 182 mm (7 in.).

Vacuum line layout

Note. Always replace gaskets and seals.

The following list pertains to (Scheme 6).

Ventilation line To fuel tank
Evaporative Emission (EVAP) canister Located at bottom of spare wheel well underneath vehicle
Leak Detection Pump (LDP) -V144- Located in left-rear wheelhousing
Air cleaner For Leak Detection Pump (LDP)
Intake Manifold Tuning (IMT) valve -N156- To vacuum solenoid of intake manifold tuning valve
Fuel pressure regulator
Combination valve, left For Secondary Air Injection (AIR) At rear of left cylinder head
Engine
Vacuum reservoir
Intake manifold
Intake manifold tuning vacuum solenoid For intake manifold tuning valve
Secondary Air Injection (AIR) pump motor -V101- Intake air from air cleaner
Air cleaner With connection for intake air for secondary air injection pump
Throttle body
Combination valve, right For secondary air injection Located at rear of right cylinder head
Check valve
Secondary Air Injection (AIR) solenoid valve -N112- Control line to combination valves left and right
Evaporative Emission (EVAP) canister purge regulator valve -N80- Mounted to air cleaner housing

Secondary Air Injection (AIR) system

Check Diagnostic Trouble Code (DTC) memory. See «CHECK DTC MEMORY (SCAN TOOL FUNCTION 02)»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-28l-v6-aha)
Conduct output Diagnostic Test Mode (DTM). See «OUTPUT DIAGNOSTIC TEST MODE (SCAN TOOL FUNCTION 03)»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-28l-v6-aha__output-diagnostic-test-mode-scan-tool)
Conduct "Basic Setting" (scan tool function 04). «BASIC SETTING (SCAN TOOL FUNCTION 04)»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-28l-v6-aha__basic-setting-scan-tool-function-04)

Note. The secondary air injection system injects air behind the exhaust valves during a cold start. Cold start means engine coolant temperature of - 10° C to +45° C (14° F to 113° F). The need for secondary air is triggered by the Motronic Engine Control Module (ECM) -J220- via the Secondary Air Injection (AIR) Injection pump relay -J299- to the Secondary Air Injection (AIR) solenoid valve -N112- and the two combination valves. When "Basic Setting" (scan tool function 04) is initiated, a diagnosis for the secondary air injection system can be carried out. The diagnostics consists of a flow test and a leak test.

Flow test

During the flow test, the oxygen sensor control is switched off (engine runs rich at that time). At the same time the secondary air injection pump is switched on, injecting fresh air into the exhaust manifold which increases the oxygen content in the exhaust gas. The oxygen sensor now measures a lean mixture. To pass the diagnostic test, the oxygen sensor must measure a lean mixture for a certain time. Passing the test means that the secondary air injection system delivers enough air and the secondary air injection system is OK.

Secondary Air Injection (AIR) system, overview

The following list pertains to see scheme 7.

Engine Control Module (ECM) -J220
Air cleaner Connection for intake air of Secondary Air Injection (AIR) Pump
Secondary Air Injection (AIR) pump motor -V101
Connection Between air cleaner and secondary air injection pump Removing, see «SECONDARY AIR INJECTION (AIR) SYSTEM COMPONENTS, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-controls-28l-v6-aha-atq__secondary-air-injection-air-system-components)
Vacuum line Control line between secondary Air Injection (AIR) solenoid valve -N112- and combination valves
Connection tube From secondary air injection pump to combination valves
Combination valves Located at rear of left and right cylinder heads Removing and installing, see «SECONDARY AIR INJECTION (AIR) SYSTEM COMPONENTS, REMOVING AND INSTALLING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-controls-28l-v6-aha-atq__secondary-air-injection-air-system-components)
Engine
Right exhaust manifold
Left exhaust manifold
Secondary Air Injection (AIR) solenoid valve -N112
Vacuum reservoir Located in left-front wheelhousing

Scheme 1

Scheme 1: Secondary Air Injection (AIR) system, checking

Checking secondary Air Injection (AIR) pump motor -V101- Conduct "Output Diagnostic Test Mode" (function 03) for Secondary Air Injection (AIR) pump relay -J299-. See «OUTPUT DIAGNOSTIC TEST MODE (SCAN TOOL FUNCTION 03)»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-28l-v6-aha__output-diagnostic-test-mode-scan-tool) During output DTM, the individual checks are performed until the "-->" button is pressed to advance through the program sequence. The motor for the air pump is triggered for 10 seconds (the running noise of the motor should be audible. If the secondary Air Injection (AIR) pump motor -V101- does not run, check whether is actuated: Select "End output" scan tool function 06. Disconnect 2-pin harness connector from secondary Air Injection (AIR) pump motor -V101-. Connect VAG1527B LED voltage tester between connector terminals -1- and -2- using adapters from VW1594 connector test kit. see scheme 8: Identifying Secondary Air Injection (AIR) Pump Motor Harness Connector Terminals Switch ignition on. Conduct "Output Diagnostic Test Mode" (function 03) for Secondary Air Injection (AIR) pump relay -J299-. See «OUTPUT DIAGNOSTIC TEST MODE (SCAN TOOL FUNCTION 03)»(/audi/a6/c5-1997-2001/remont/testing-diagnostics/#on-board-diagnostic-obd-28l-v6-aha__output-diagnostic-test-mode-scan-tool) LED voltage tester must light up for about 10 seconds If LED voltage tester lights up (power supply is OK): 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-controls-28l-v6-aha-atq__secondary-air-injection-air-system-components). If LED does not light up: Check wiring for continuity between secondary Air Injection (AIR) pump motor -V101- and secondary Air Injection (AIR) pump relay -J299- according to wiring diagram. Check for short circuit to Ground according to wiring diagram. If wiring is OK: Check secondary Air Injection (AIR) pump relay -J299-, see «SECONDARY AIR INJECTION (AIR) SYSTEM, CHECKING»(/audi/a6/c5-1997-2001/remont/exhaust/#exhaust-system-emission-controls-28l-v6-aha-atq), section "B", found below.
Checking secondary Air Injection (AIR) pump relay -J299- NOTE: The relay and the fuse for the air pump are located in the E-box in the left side of the plenum chamber. See appropriate System Wiring Diagrams article

Test requirements

Fuel pump relay OK
Fuse for secondary Air Injection (AIR) pump relay -J299- OK
Ignition switched off

Scheme 2

Remove secondary Air Injection (AIR) pump relay -J299- from relay panel.
Connect VAG1527B LED voltage tester between terminal (B+) of relay socket and Ground (GND). LED voltage tester must light up
Connect VAG1527B LED voltage tester between terminal 4 (B+) of relay socket and Ground (GND) and operate starter motor. see scheme 9: Identifying Secondary Air Injection (Air) Pump Relay Terminals In Relay Carrier LED voltage tester must light up

If LED voltage tester does not light up

Repair open circuit according to applicable wiring diagram.

If LED voltage tester lights up

Checking triggering of secondary Air Injection (AIR) pump relay -J299

Scheme 3

Switch ignition on.
Connect VAG1527B LED voltage tester between terminal 8 (B+) of relay socket and Ground. LED voltage tester must light up
Connect VAG1527B LED voltage tester between terminals -6- and -8- of relay socket and/or terminal -6- of relay socket and Ground. see scheme 10: Identifying Terminals Of Secondary Air Injection (Air) Pump Relay Terminals In Relay Carrier
Conduct "Output Diagnostic Test Mode" (function 03) for secondary Air Injection (AIR) pump relay -J299-.

See OUTPUT DIAGNOSTIC TEST MODE (SCAN TOOL FUNCTION 03)

When secondary Air Injection (AIR) pump relay -J299- is triggered

LED voltage tester must light up

If LED voltage tester lights up

Replace secondary Air Injection (AIR) pump relay -J299-.

If LED voltage tester stays lit constantly or does not light up at all

Connect VAG1598/22 test box to ECM harness connector.

See VAG1551/VAG1552 SCAN TOOL (ST), CONNECTING AND SELECTING "ENGINE ELECTRONICS" ADDRESS WORD 01

If LED voltage tester stays on brightly

Check wiring from terminal -6- of relay socket to test box socket 30 for short circuit to ground.

If LED voltage tester does not light

Check wiring from terminal -6- of relay socket to test box socket 30 for open circuit.
If necessary, repair ground connection or open circuit between terminal -6- of relay socket and test box socket 30.

If wiring is OK

Replace Motronic ECM -J220-, create and readiness code.

See ON BOARD DIAGNOSTIC (OBD) .

Electrical test

Disconnect harness connector for secondary Air Injection (AIR) solenoid valve -N112-.
Select resistance range on multimeter (Fluke 83 or equivalent) and measure between terminals of valve. Specified value: 25-35 Ohms (Ohm;)

If specified value is not attained

Replace secondary Air Injection (AIR) solenoid valve -N112-.

Measuring Resistance Between Terminals Of Secondary Air Injection (Air) Solenoid Valve. Scheme 4

Scheme 4: Measuring Resistance Between Terminals Of Secondary Air Injection (Air) Solenoid Valve

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

Disconnect harness connector for secondary Air Injection (AIR) solenoid valve -N112-.
Connect VAG1527B LED voltage tester between connector terminal -1- (B+) and engine Ground.
Conduct "Output Diagnostic Test Mode" (function 03) for Fuel Pump (FP) relay -J17-.

See OUTPUT DIAGNOSTIC TEST MODE (SCAN TOOL FUNCTION 03)

If LED voltage tester does not light up

Check fuse for secondary Air Injection (AIR) solenoid valve -N112
Check wiring for continuity between connector terminal -1- and fuse according to wiring diagram. Specified value: max. 0.5 Ohms (Ohms;)
Check fuel pump relay and activation

See FUEL PUMP RELAY AND CONNECTIONS, CHECKING

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

Connect VAG1527B LED voltage tester between terminal -1- (B+) and terminal -2- of connected harness connector for secondary Air Injection (AIR) solenoid valve.
Conduct "Output Diagnostic Test Mode" (function 03) for secondary Air Injection (AIR) solenoid valve -N112-.

See ON BOARD DIAGNOSTIC (OBD)

LED voltage tester must blink

If LED voltage tester does not blink or if light stays on

Connect VAG1598/22 test box to ECM harness connector.

See VAG1551/VAG1552 SCAN TOOL (ST), CONNECTING AND SELECTING "ENGINE ELECTRONICS" ADDRESS WORD 01

If LED voltage tester stays on

Check wiring between harness connector terminal -2- and test box socket 33 for short circuit to Ground.

If LED voltage tester does not blink

Check wiring between harness connector terminal -2- and test box socket 33 for continuity.
If necessary, repair short circuit to Ground or open circuit between harness connector terminal -2- and test box socket 33.

If wiring is OK

Replace Motronic ECM -J220-, create and check readiness code.

See ON BOARD DIAGNOSTIC (OBD)

Secondary Air Injection (AIR) system components, removing and installing

Component locations, see SECONDARY AIR INJECTION (AIR) SYSTEM, OVERVIEW .

Fuel injection and ignition components.

See MOTRONIC MULTIPORT FUEL INJECTION (MFI) AND IGNITION SYSTEM .

Note. Always replace gaskets and seals.

A - Combination valve, left

Remove engine coolant expansion tank from bracket.
Disconnect vacuum line -1-.
Disconnect connection tube -2- from combination valve. Tightening torque: 10 Nm (7 ft lb).
Remove bolts -3- for combination valve from cylinder head and remove valve. Tightening torque: 10 Nm (7 ft lb).

Removing Combination Valve, Left. Scheme 5

Scheme 5: Removing Combination Valve, Left

Scheme 6

Scheme 6: B - Combination valve, right

Remove air duct between Mass Air Flow (MAF) sensor and air intake elbow (three -arrows- on right).
Remove air intake elbow.
Disconnect harness connector for Evaporative Emission (EVAP) canister purge regulator valve (left -arrow-).
Turn connector tube for Secondary Air Injection (AIR) pump 1/4 -turn (90°) to right and disconnect.
Remove air cleaner housing.
Remove vacuum line -1-.
Disconnect connection tube -2- from combination valve. Tightening torque: 10 Nm (7 ft lb).
Remove bolts -3- for combination valve from cylinder head and if necessary, remove bracket -4-. Tightening torque: 10 Nm (7 ft lb). see scheme 19: Removing Combination Valve Right
Remove combination valve.

C - Secondary Air Injection (AIR) pump motor

Remove noise insulation panel (arrows).
Remove front bumper. See «FRONT BUMPER»(/audi/a6/c5-1997-2001/remont/exterior-body-panels/#bumper) or «FRONT BUMPER (AUDI RS6)»(/audi/a6/c5-1997-2001/remont/exterior-body-panels/#bumper)
Move lock carrier to service position. See «LOCK CARRIER, SERVICE POSITION»(/audi/a6/c5-1997-2001/remont/exterior-body-panels/#body-front__lock-carrier-service-position)
Remove air duct to generator at front of air shroud.
Disconnect connection at air pump (left arrows), cut cable ties.
Remove three bolts(lower right arrows) but do not remove nuts.
Remove pump toward rear from bracket.
Remove connection line to air cleaner.
Turn connector tube for Secondary Air Injection (AIR) pump 1/4 -turn (90°) to right and disconnect.
Remove air pump.

Installing

Installation is the reverse of removal.

Exhaust System, Emission Controls (2.8l v6 Aha, Atq) Audi A6 C5