Oxygen Sensor Heater Z29, Checking

Oxygen Sensor Heater Z29, Checking

• Oxygen Sensor (O2S) Heater (Z29) is part of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) and cannot be replaced separately.

• When servicing electrical harness connector terminals for the Heated Oxygen Sensor (HO2S), use only gold-plated terminals.

Special tools, testers and auxiliary items required

• Multimeter

• wiring diagrams

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

Test requirements

• Fuse for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) 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 vehicle floor cover - arrows -.





- Disconnect the 4-pin electrical harness connector - 1 - from the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130).





Checking internal resistance

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- Using a Multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) component terminals 1 to 2 for resistance.





Specified resistance: 1.0 to 20.0 ohms (at approx. 20°C)

If the specified value is not obtained:

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

If the specified value is obtained:

Checking voltage supply

- Switch the ignition on.

- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector terminal 1 to Motronic Engine Control Module (ECM) Power Supply Relay (J271) socket 87 for voltage.





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 Adapter Cable (121 Pin) (VAG1598/31 ).

If the manufacturers test box is not being used. Perform the following step.

- Remove the Engine Control Module (ECM) (J623). 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) (G130) electrical harness connector terminal 2 to the Engine Control Module (ECM) (J623) electrical harness connector T121 terminal 6 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, 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 ] Readiness Code.

- 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 => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.

Final procedures

After the 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, Setting ] Readiness Code, Setting.

End of Diagnosis.