Heated Oxygen Sensor, Checking

Heated Oxygen Sensor, 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
- Fuse S344 OK.
- Engine Component Power Supply Relay J757 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. General Diagnosis

Start diagnosis
- Perform the function test in Diagnostic Mode 06. Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions

If 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 - 2 -.
- Start the engine.







- 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 was not obtained:

Checking wiring

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 Engine Control Module (ECM) J623.







- Using a Multimeter , check the Heated Oxygen Sensor (HO2S) G39 electrical harness connector terminals to the Engine Control Module (ECM) J623 electrical harness connector T94 terminals for resistance.

Heated Oxygen Sensor (HO2S) Engine Control Module (ECM) J623
G39 electrical harness electrical harness connector T94
connector terminals terminals or test box sockets
1 60
2 61
5 81
6 82

Specified value: 1.5 Ohms Max.

If the specification was not obtained:
- Check the wiring for an open circuit, 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 detected in the wiring and the voltage supply was OK:
- Erase the 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. 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 not OK:
- Replace the Engine Control Module (ECM) J623.
- 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. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

End of diagnosis