Oxygen Sensor Heaters After Catalytic Converter, Checking
Oxygen Sensor Heaters after Catalytic Converter, Checking
The following procedure is used to diagnose Oxygen Sensor (O2S) 1 (behind Three Way Catalytic Converter (TWC)) Heater (Z29) for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) and Oxygen Sensor (O2S) 2 (behind Three Way Catalytic Converter (TWC)) Heater (Z30) for Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) (G131).
• Vehicle must be raised before electrical harness connector for the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) and Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) (G131) is accessible.
• 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) fuse 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
- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.
Start diagnosis
- Remove the right vehicle floor cover - arrows -.
Checking internal resistance
- Disconnect the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector - 1 - or the Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) (G131) electrical harness connector - 2 -.
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) terminals 1 to 2 for resistance.
Specified value: 1.0 to 20.0 ohms (at approx. 20° C)
If the specification was not obtained:
- Replace the faulty Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC).
If the specification was obtained:
Checking voltage supply
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector terminal 1 to the Fuel Pump (FP) 2 Relay (J49) - R4 -terminal 2/87 for an open circuit.
Specified value: Battery voltage.
If the specification was not obtained:
- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).
- Check the electrical harness connector for damage, corrosion, lose or broken terminals.
- If necessary, repair the faulty wiring connection.
If the specification was obtained:
Checking Ground (GND) activation
If the manufacturers test box is being used. Perform the following step.
- Install the test box. Refer to repair information.
If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) (J220). Refer to => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) electrical harness connector to the Motronic Engine Control Module (ECM) (J220) electrical harness connector T121 for an open circuit.
Specified value: 1.5 ohms max.
If the specification was not obtained:
- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).
- Check the electrical harness connector for damage, corrosion, lose or broken terminals.
- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring and if the voltage supply was OK:
- Replace the Motronic Engine Control Module (ECM) (J220). Refer to => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.
- Install the right vehicle floor cover.
Final procedures
After repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.
- End of diagnosis.