Oxygen Sensor Heater Z19, Checking

Oxygen Sensor Heater Z19, Checking

• Oxygen Sensor (O2S) Heater (Z19) is part of Heated Oxygen Sensor (HO2S) (G39) 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 diagram

• When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S) (G39), use only gold-plated terminals.

Test requirements

• Fuse for Heated Oxygen Sensor (HO2S) (G39) 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 engine cover with air filter.

Checking internal resistance

- Disconnect the Heated Oxygen Sensor (HO2S) (G39 ) electrical harness connector - 1 -.





- Using a multimeter, check the Heated Oxygen Sensor (HO2S) (G39) terminals 3 to 4 for an open circuit.

Specified value: 2.5 to 10.0 ohms (at approx. 20° C)

If the specification was not obtained:

- Replace Heated Oxygen Sensor (HO2S) (G39).

If the specified value is obtained:

Checking voltage supply

- Switch the ignition on.

- Using a multimeter, check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminal 4 to the Motronic Engine Control Module (ECM) Power Supply Relay (J271) socket 87 for voltage.









- Switch the ignition off.

Specified value: Battery voltage.

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 105 Pin (VAG1598/42).

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 HO2S Sensor (G39) electrical harness connector terminal 3 to the Engine Control Module (ECM) (J623) electrical harness connector T121 terminal 5 for an open circuit.









Specified resistance 1.5 ohms max.

If the specification is not obtained:

- Check the wiring for a short circuit to Battery positive (+) or an open circuit.

- If necessary, repair the 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.