Oxygen Sensor Heater Behind Catalytic Converter, Checking
Oxygen Sensor Heater Behind Catalytic Converter, Checking
• Vehicle must be raised before electrical harness connector for the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) is accessible.
• When servicing terminals in harness connector of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130), use only gold-plated terminals.
Special tools, testers and auxiliary items required
• multimeter.
• Wiring diagram.
Test requirements
• The Oxygen Sensor (O2S) Heater Behind Three Way Catalytic Converter (TWC) (G130) fuse 21 in Fuse Panel B is OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Ignition switched off.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check
Start diagnosis
- Remove the right vehicle floor cover - arrows -.
Checking internal resistance
- Disconnect the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector - arrow -.
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector terminals 1 to 2 for resistance.
Specified value: 1.0 to 20.0 ohms (at approx. 20° C)
If the specified value was Not obtained:
- Replace the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130). Refer to the repair information.
If the specified value was obtained:
Checking voltage supply
- Turn the ignition switch ON
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector terminal 1 to engine ground.
Specified value: Battery voltage.
If the specified value was Not obtained:
- Check the wiring for an open, high resistance, short circuit to each other, or Ground (GND).
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
If the specified value was obtained:
Checking Ground (GND) activation
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). Refer to the repair information.
- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) (G130) electrical harness connector terminal to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T94 for an open circuit according to the chart below.
Specified value: 1.5 ohms max.
If the specified value was Not obtained:
- Check the wiring for an open or high resistance.
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring:
- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the repair information.
- Install the right vehicle floor cover.
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 Modes 01 - 09.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.