With Generic Scan Tool

Heated Oxygen Sensor (HO2S) G39 / Heated Oxygen Sensor (HO2S) 2 G108, checking

The following procedure is used to diagnose both Heated Oxygen Sensor (HO2S) G39 and Heated Oxygen Sensor (HO2S) 2 G108

Note: Use only gold-plated terminals when servicing terminals in the electrical harness connectors of the Heated Oxygen Sensor (HO2S) G39 and Heated Oxygen Sensor (HO2S) 2 G108.

Special tools, testers and auxiliary items required
- Multimeter
- Wiring diagram.

Test requirements

- The Heated Oxygen Sensor (HO2S) G39 / Heated Oxygen Sensor (HO2S) 2 G108 fuses OK.
- The Heated Oxygen Sensor (HO2S) G39 / Heated Oxygen Sensor (HO2S) 2 G108 Heater circuits OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Exhaust system between catalytic converter and cylinder head properly sealed.
- Coolant Temperature at least 80�C.

Test procedure

- Perform preliminary check to verify the customers complaint.

Start diagnosis

Function test

- Perform the function test in Diagnostic Mode 06. Diagnostic Mode 06: Checking Test Results of Components That Are Not Continuously Monitored

If the specified values are obtained:

- End diagnosis and switch the ignition off.

If the specified values are not obtained:

Checking primary voltage

- Disconnect the Heated Oxygen Sensor (HO2S) G39 electrical harness connector - Upper Arrow - or the Heated Oxygen Sensor (HO2S) 2 G108 electrical harness connector - Lower Arrow - .

- Using a multimeter, check the Heated Oxygen Sensor (HO2S) electrical harness connector terminals 3 to 4 for voltage.

Specified value: 0.40 to 0.50 Volts

- Switch the ignition off.

If the specified value was not obtained:

- Replace the Heated Oxygen Sensor (HO2S) G39 or the Heated Oxygen Sensor (HO2S) 2 G108.

If the specified value was obtained:

Checking wiring

If the manufacturers test box is being used. Perform the following step.

- Install the Test Box 80 Pin VAG1598/22 (Engine Code AHA).

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

- Remove the Engine Control Module (ECM) J220.

- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) G39 or the Heated Oxygen Sensor (HO2S) 2 G108 electrical harness connector terminals to the Engine Control Module (ECM) J220 electrical harness connector terminals for an open circuit.

(Engine Code AHA)

Specified value: 1.5 Ohm 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.

If no malfunction is found in the wiring:

- Erase the DTC memory. Diagnostic Mode 04: Reset/Delete Diagnostic Data

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Audi Drive Cycle/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 Engine Control Module (ECM) J220.

- Assembly is performed in the reverse of the removal.

Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

End of diagnosis