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Oxygen Sensors and Sensor Regulation After Catalytic Converter, Checking



Oxygen Sensors and Sensor Regulation after Catalytic Converter, Checking

The following procedure is used to diagnose both Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 and the Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131

NOTE:
- Vehicle must be raised before the electrical connector of the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 and Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131 is accessible.
- When servicing terminals 3 and 4 in the electrical harness connector of the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 and Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131 , 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 and Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131 Engine Electronics Fuse S282 OK.
- Oxygen Sensor (O2S) 1 (behind Three Way Catalytic Converter (TWC)) Heater Z29 and Oxygen Sensor (O2S) 2 (behind Three Way Catalytic Converter (TWC)) Heater Z30 OK.
- 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 degrees C.

Function test
- Connect scan tool.
- Start the engine and let it run at idle.
- Select "Diagnostic mode 6: Check test results of components that are not continuously monitored".
- Select "Test-ID 02: Oxygen sensor monitoring behind catalytic converter".
- Select following Test-IDs.
- Check the specified values at idle.







If the specified values are obtained:
- End diagnosis and switch ignition off.

If the specified values are not obtained:

Procedure for accessing the Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131 electrical harness.







- Remove the left side engine compartment cover - 1 -.
- Remove the coolant expansion tank screw - arrow -.







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







- Disconnect the Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131 electrical harness connector - 1 -.

Procedure for accessing the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 electrical harness.







- Remove the cover on the right side of the engine compartment - 1 -.







- Remove the air intake duct - arrows -.







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

Checking primary voltage
- Switch the ignition on.







- Using a multimeter , check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 electrical harness connector terminals 3 to 4 for voltage.

Specified value: 0.400 to 0.500 Volts

- Switch the ignition off.

If the specified value was obtained:
- Replace the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 or Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131.

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 Motronic Engine Control Module (ECM) J623.







- Using a Multimeter , check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 electrical harness connector terminals to the Motronic Engine Control Module (ECM) J623 or Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131 electrical harness connector T121 terminals for an open circuit.

Terminal Engine Control Module (ECM) J623
G130 electrical connector T121
terminals or test box sockets
3 68
4 69

Terminal Engine Control Module (ECM) J623
G131 electrical connector T121
terminals or test box sockets
3 10
4 11

Specified value: 1.5 Ohms Max.

If the specification was 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 found in the wiring:
- Replace the Motronic Engine Control Module (ECM) J623.

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
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