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.