Oxygen Sensor: Testing and Inspection

Heated Oxygen Sensor, Checking

Special tools, testers and auxiliary items required

• Multimeter

• wiring diagrams

• All manufacturer's special tools as well as common tools may contain a manufacturer specific part number. These tools may be substituted with an equivalent aftermarket tool, or are available for purchase from the manufacturer.

• Manufacturers special tools as well as common tools that contain a manufacturer specific part number may be referenced in the test procedure illustrations, showing the tool use or installation. If the manufacturer specific tool is not being used, an equivalent aftermarket tool may be installed in the same manner as the manufacturer's special tool.

• 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.

• 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

- Connect the scan tool.

- Start engine and let it run at idle.

- Select "Diagnostic mode 6: Check test results of components that are not continuously monitored".

- Select "Test-ID 01: Heated Oxygen Sensor".

- Select "Test-ID 131: Dynamic test" and check whether specified values are obtained.





- End diagnosis and switch ignition off.

If specified values are not obtained:

- Check Heated Oxygen Sensor (HO2S) (G39) wiring.

Testing of oxygen sensor wires

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

- Disconnect the 6-pin electrical harness connector from the Heated Oxygen Sensor (HO2S) (-G39-).

- Using a Multimeter, check the following wiring connections 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.

If no malfunctions are found in wiring:

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

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 ] Readiness Code.