Oxygen Sensor After Catalytic Converter Heater Circuit, Checking

Oxygen Sensor After Catalytic Converter Heater Circuit, Checking

• Vehicle must be raised before electrical harness connector for the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) is accessible.

• When servicing terminals in harness connector of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130), use only gold-plated terminals.

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• Fuse (S18) 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 => [ Preliminary Check ] Preliminary Check.

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 -.





- 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 Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130).

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 Ground (GND) for Voltage.





Specified value: Battery voltage.

If the specification was not obtained:

- Check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector terminal 1 to the Engine Component Power Supply Relay (J757) terminal 87 for an open circuit, or a short circuit to Ground (GND).

- 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). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T94 for resistance.









Specified value: 1.5 ohms max.

If the specification was not obtained:

- Check the wiring for an open circuit, short circuit to each other, Battery (+), or 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. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ 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). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- 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. 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 ] Monitors, Trips, Drive Cycles and Readiness Codes.