HO2S Front Oxygen Sensor Bank 2 Sensor 1, Checking
Diagnostic Procedures
HO2S Front Oxygen Sensor Bank 2 Sensor 1, Checking
The following procedure is used to diagnose both HO2S Oxygen Sensor Bank 1 Sensor 1 (G39) and HO2S Oxygen Sensor Bank 2 Sensor 1 (G108)
• Use only gold-plated terminals when servicing terminals in the electrical harness connectors of the HO2S Oxygen Sensor Bank 1 Sensor 1 (G39) and HO2S Oxygen Sensor Bank 2 Sensor 1 (G108).
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• The Oxygen Sensor Heater Bank 2 Sensor 1 (Z28) fuse OK.
• The Oxygen Sensor Heater Bank 2 Sensor 1 (Z28) before catalytic converter OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• A/C switched off.
• Ground connections between engine/transmission/chassis OK.
• Exhaust system between catalytic converter and cylinder head properly sealed.
• Coolant Temperature at least 80° C.
Test procedure
- Observe safety precautions. Refer to => [ Safety Precautions ] Safety Precautions
- Observe Clean Working Conditions. Refer to => [ Clean Working Conditions ] Clean Working Conditions
- 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. Refer to => [ Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions ] Diagnostic Modes 01 - 09.
- Switch the ignition off.
If the specified values were not obtained:
Start Diagnosis
- Disconnect the HO2S Oxygen Sensor Bank 2 Sensor 1 (G108) - 4 - electrical harness connector.
Checking primary voltage
- Using a multimeter, check the HO2S Oxygen Sensor Bank 2 Sensor 1 (G108) electrical harness connector terminals 1 to 5 for voltage.
Specified value: 0.40 to 0.50 V
- Switch the ignition off.
If the specified value was obtained:
- Replace the HO2S Oxygen Sensor Bank 2 Sensor 1 (G108).
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). Refer to the Repair Information.
- Using a multimeter, check the HO2S Oxygen Sensor Bank 2 Sensor 1 (G108) electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J220) electrical harness connector T94 terminals for an open circuit.
Specified value: 1.5 ohms Max.
If the specification was not obtained:
- Check the wiring for high resistance, an open or a short to voltage or ground.
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.
- Perform a road test to verify repair.
If the DTC does not return:
Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.
If the DTC does return, no malfunction is detected in the wiring and the voltage supply is OK:
- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the Repair Information.
- 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. 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 ] Readiness Code.