Oxygen Sensors After Catalytic Converter, Checking

Oxygen Sensors after Catalytic Converter, Checking

This procedure is used to diagnose Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) or Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) ( G131).

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

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) fuse OK.

• The Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) (G131) fuse OK. Refer to => [ Oxygen Sensor Heater after Catalytic Converter, Checking ] Oxygen Sensor Heater After Catalytic Converter, 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.

Function test

Perform a function test of the Heated Oxygen Sensors (HO2S). Refer to ADD LINK

If specified values are obtained:

- End diagnosis and switch the ignition off.

If the specified values are not obtained:

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.

Start diagnosis

- Disconnect the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector - 2 -.





To disconnect the Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) (G131), perform the following steps:

- Remove the screw - arrow - retaining the coolant reservoir.





- Disconnect the Engine Coolant Level (ECL) Warning Switch (F66) electrical connector from the bottom of the coolant reservoir and set aside the coolant reservoir with the coolant hoses - 1 - and - 2 - connected.

- Disconnect the Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) (G131) electrical harness connector - 2 -.





Checking primary voltage

- Using a Multimeter, check the Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) electrical harness connector terminals 3 to 4 for voltage.





- Switch the ignition on.

Specified value: 0.400 to 0.500 V.

- Switch the ignition off.

If the specified value was obtained:

- Replace the faulty Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC). Refer to Fuel Injection and Ignition Repair Information.

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. Refer to Fuel Injection and Ignition Repair Information.

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

- Remove the Engine Control Module (ECM) (J623 ). Refer to => [ ECM, Removing and Installing ] ECM, Removing and Installing.

- Using a Multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) electrical harness connector terminals to the Engine Control Module (ECM) (J623) electrical harness connector T94 terminals for an open circuit.













Specified value: 1.5 ohms Max.

If any of the specified values are 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 detected in the wiring:

- Replace the Engine Control Module (ECM) (J623 ). Refer to => [ ECM, Removing and Installing ] ECM, Removing and Installing.

Final procedures

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

1. Check the DTC memory. => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End of diagnosis.