With Generic Scan Tool

Heated Oxygen Sensor (HO2S) G39 and oxygen sensor regulation before catalytic converter, checking

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

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

Test requirements
- The Heated Oxygen Sensor (HO2S) G39 fuse OK.
- The Heated Oxygen Sensor (HO2S) G39 heater circuit before catalytic converter OK. O2 Sensor Heater Before Catalytic Converter
- 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.

Function test

- Perform the function test in Diagnostic Mode 05 and Diagnostic Mode 06.
Diagnostic Mode 5: Check Lambda Test Results
Diagnostic Mode 6: Check Test Results of Components That Are Not Continuously Monitored

Test procedure

- Perform a preliminary check to verify the customers complaint. Service and Repair

Start diagnosis

Checking primary voltage






- Remove the protective cover - arrows - and disconnect the Heated Oxygen Sensor (HO2S) G39 electrical harness connector.






- Using a multimeter, check the Heated Oxygen Sensor (HO2S) G39 electrical harness connector terminals 1 to 5 for voltage.

Specified value: 0.400 to 0.500 Volts

- Switch the ignition off.

If the specified value was obtained:

- Replace the Heated Oxygen Sensor (HO2S) G39.

If the specified value is obtained:

Checking wiring

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

- Install the test box Test Box 105 Pin VAG1598/31.

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

- Remove the Motronic Engine Control Module (ECM) J220. Service and Repair






- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) G39 electrical harness connector terminals to the Motronic Engine Control Module (ECM) J220 electrical harness connector T121 terminals 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, lose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring:

- Erase the DTC memory. Diagnostic Mode 4: Reset/Erase Diagnostic Data

- 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 MFI Engine Control Module (ECM) J220. Service and Repair

- Assembly is performed in the reverse of the removal.

Final procedures

After the 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 diagnosis.