Oxygen Sensor Behind Three Way Catalytic Converter, Checking

Oxygen Sensor behind Three Way Catalytic Converter, Checking

Special tools, testers and auxiliary items required

• Multimeter

• wiring diagrams

• When servicing terminals in harness connector of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130), use only gold-plated terminals.

Test requirements

• Fuse for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) OK.

• Oxygen Sensor (O2S) 1 (behind Three Way Catalytic Converter (TWC)) Heater ( Z29) OK. Refer to => [ Oxygen Sensor Heater Z29, Checking ] Oxygen Sensor Heater Z29, Checking.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, selector lever in position " P" or "N".

• 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 a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Function test

- Perform the function test in Diagnostic Mode 06 => [ Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions ] Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions.

If the specified values are not obtained:

Start diagnosis

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

- Disconnect the 4-pin electrical harness connector - 1 - from the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130).





- Using a Multimeter, check the component terminals 3 to 4 for voltage.





Specified value: 0.400 to 0.500 Volts

- Switch ignition off.

If specified value is not obtained:

- Replace Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130).

If specified value is obtained:

Testing of oxygen sensor wires

- Using the 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.

- 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.

- 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. 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.