Oxygen Sensor 1 Heater After Catalytic Converter, Checking

Oxygen Sensor 1 Heater After Catalytic Converter, Checking

NOTE:
- Oxygen Sensor (O2S) 1 (behind Three Way Catalytic Converter (TWC)) Heater Z29 is part of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 and cannot be replaced separately.
- 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
- Fuse S344 OK.
- Engine Component Power Supply Relay J757 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. General Diagnosis

Start diagnosis







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

Checking internal resistance
- Using the Multimeter V.A.G 1526 A or equivalent, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 electrical harness connector terminals 1 to 2 for resistance.







Specified resistance: 1.0 to 20.0 Ohms (at approx. 20 degrees C)

If the specified value is not obtained:
- Replace Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130.

If the specified value is obtained:

Checking voltage supply
- Crank the engine (engine may run).







- Using a multimeter , check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 electrical harness connector terminal 1 to Ground (GND) for voltage.

Oxygen Sensor (O2S) Behind Measure to
Three Way Catalytic Converter
(TWC) G130 electrical harness
connector terminal
1 Ground (GND)

- Switch the ignition off.

Specified value: Battery voltage.

If the specification was not obtained:
- Check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 electrical harness connector terminal 1 to the Motronic Engine Control Module (ECM) Power Supply Relay J271 socket 2/87 an open circuit, a short circuit to each other, Battery (+), or Ground (GND).
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.

If the specification 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 Engine Control Module (ECM) J623.







- Using a multimeter , check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 electrical harness connector terminal 2 to the Engine Control Module (ECM) J623 electrical harness connector T94 terminal 7 for resistance.

Oxygen Sensor (O2S) Behind Engine Control Module (ECM)
Three Way Catalytic Converter J623 electrical harness connector
(TWC) G130 electrical harness T94 terminal or test box socket
connector terminal
2 7

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, loose or broken terminals.
- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:
- Erase the 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. Monitors, Trips, Drive Cycles and Readiness Codes
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the Engine Control Module (ECM) J623.
- Assembly is performed in the reverse of the removal.

Final procedures
After repair work, the following work steps must be performed in the mentioned 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

End of diagnosis