Oxygen Sensor (O2S) 1 (Behind Three Way Catalytic Converter (TWC) Heater Z29, Checking
Oxygen Sensor (O2S) 1 (Behind Three Way Catalytic Converter (TWC) Heater Z29, 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.
NOTE: When servicing terminals in harness connector of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) 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. Preliminary Check
Start diagnosis
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 - 3 -.
- 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 degrees 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
Switch the ignition on.
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) electrical harness connector terminal 1 to the Engine Component Power Supply Relay J757 terminal 2/87 for voltage.
Oxygen Sensor (O2S) Behind Engine Component Power Supply
Three Way Catalytic Relay J757 electrical harness
Converter (TWC) electrical connector terminal
harness connector terminal
1 2/87
Specified value: Battery voltage.
Switch the ignition off.
If the specification was not obtained:
- Check the wiring for a short circuit to each other, Ground (GND) or an Open circuit.
- Check the electrical harness connector for damage, corrosion, loose 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.
If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J623.
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) electrical harness connector to the Engine Control Module (ECM) J623 electrical harness connector T94 for an open circuit.
Oxygen Sensor (O2S) Behind Engine Component Power Supply
Three Way Catalytic Converter Relay J757 electrical harness
(TWC) G130 electrical connector terminal
harness connector terminal
2 7
Oxygen Sensor (O2S)2 Behind Engine Component Power Supply
Three Way Catalytic Converter Relay J757 electrical harness
(TWC)G131 electrical harness connector terminal
Connector terminal
2 29
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, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
- Erase the DTC memory. Diagnostic Modes 01 - 09.
- Perform a road test to verify repair.
If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- End diagnosis.
If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the Motronic Engine Control Module (ECM) J623.
- Assembly is performed in the reverse of the removal.
Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check the DTC memory. Diagnostic Modes 01 - 09
2. If necessary, erase the DTC memory. Diagnostic Modes 01 - 09
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
End of Diagnosis