RS 4 Quattro Cabriolet V8-4.2L (BNS) (2008)
Oxygen Sensor: Testing and Inspection
Oxygen Sensor 2 Heater, Checking
Oxygen Sensor 2 Heater, Checking
The following procedure is used to diagnose Oxygen Sensor (O2S) 2 Heater (Z28) for Heated Oxygen Sensor (HO2S) 2 (G108) which is controlled
by the Engine Control Module (ECM) 2 (J624).
‹› When servicing electrical harness connector terminals for the Heated Oxygen Sensors, use only gold-plated terminals.
Special tools, testers and auxiliary items required
‹› Multimeter.
‹› Wiring diagram.
Test requirements
‹› Heated Oxygen Sensor (HO2S) Circuit Breaker (S73 ) 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.
Test procedure
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Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] See: Computers and Control Systems/Testing
and Inspection/Initial Inspection and Diagnostic Overview/General Diagnosis.
Start diagnosis
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Raise the vehicle.
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Disconnect the Heated Oxygen Sensor (HO2S) 2 ( G108) electrical harness connector- 4 -.
Checking internal resistance
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Using a multimeter, check the Heated Oxygen Sensor (HO2S) 2 (G108) terminals 3 to 4 for resistance.