S4 Quattro Wagon V8-4.2L (BHF) (2008)
Oxygen Sensor: Testing and Inspection
Oxygen Sensors After Catalytic Converter, Checking Heater
Oxygen Sensors after Catalytic Converter, Checking Heater
The following procedure is used to diagnose Oxygen Sensor (O2S) 1 (behind Three Way Catalytic Converter (TWC)) Heater ( Z29 ) and Oxygen
Sensor (O2S) 2 (behind Three Way Catalytic Converter (TWC)) Heater (Z30).
‹› When servicing terminals in harness connector of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) and Oxygen
Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) (G131), use only gold-plated terminals.
Special tools, testers and auxiliary items required
‹› Multimeter.
‹› Wiring diagram.
Test requirements
‹› The Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) and Oxygen Sensor (O2S) 2 Behind Three Way Catalytic
Converter (TWC) (G131) Engine Electronics Fuse (S282) OK.
‹› Battery voltage at least 12.5 volts.
‹› All electrical consumers such as, lights and rear window defroster, switched off.
‹› Vehicles with automatic transmission, shift selector lever into position " P" or "N".
‹› A/C switched off.
‹› Ground (GND) connections between engine/transmission/chassis OK.
‹› Ignition switched off.
Procedure for accessing Oxygen Sensor (O2S) 2 Heater (Z30) electrical harness.
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Remove the left side engine compartment cover - 1 -.
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Remove the coolant expansion tank screw - arrow -.
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Disconnect the electrical connector from the Engine Coolant Level (ECL) Warning Switch (F66) and set aside coolant reservoir with coolant hoses
- 1 -and - 2 - connected.