Heated Oxygen Sensor before Catalytic Converter, Checking
Heated Oxygen Sensor before Catalytic Converter, Checking
This procedure is used to check both Heated Oxygen Sensors (HO2S) (-G39-, -G108-)
• Use only gold-plated terminals when servicing terminals in the electrical harness connectors of the Heated Oxygen Sensor (HO2S) (G39, G108).
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• Fuses for engine electronics OK.
• Battery voltage at least 12.5 V.
• All electrical consumers such as, lights and rear window defroster, switched off (radiator fan must NOT run during test).
• Ground (GND) connections between engine/transmission/chassis OK.
• Oxygen sensor heater OK.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• The exhaust system free of leaks.
• The parking brake engaged.
• The A/C switched off.
• The coolant temperature at least 80 °C.
• Ignition switched off.
Test procedure
- Perform a preliminary check to verify the customer's complaint. Refer to => [ Preliminary Check ] Preliminary Check.
- Perform the function test in Diagnostic Mode 06. Refer to => [ Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions ] Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions.
If specified values are obtained:
- End diagnosis and switch the ignition off.
If the specified values are not obtained:
Checking primary voltage
- Disconnect the 6-pin electrical harness connector - 1 - from the Heated Oxygen Sensor (HO2S) (-G39-) and Oxygen Sensor (O2S) Heater (-Z19-) (bank 1, sensor 1).
To test the Heated Oxygen Sensor (HO2S) (-G108-) (bank 2, sensor 1), perform the following steps:
- Remove the screw - arrow - retaining the coolant reservoir.
- Disconnect the electrical connector from Engine Coolant Level (ECL) Warning Switch (F66) at the bottom of the coolant reservoir and set aside the coolant reservoir with the coolant hoses - 1 - and - 2 - connected.
- Disconnect the 6-pin electrical harness connector - 1 - from the Heated Oxygen Sensor (HO2S) (-G108-) and Oxygen Sensor (O2S) Heater (-Z28-) (bank 2, sensor 1).
The test procedures for the Heated Oxygen Sensor (HO2S) (-G39-) are the same for the Heated Oxygen Sensor (HO2S) (-G108-).
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminals 4 to 6 for voltage.
Specified value: 0.400 to 0.500 V
- Switch the ignition off.
If the specified value was not obtained:
- Replace the Heated Oxygen Sensor (HO2S) (G39)
If the specified value was obtained:
Checking wiring
If the manufacturers test box is being used, perform the following step.
- Connect the Test Box 105 Pin (VAG1598/42) with Adapter Cable (1598/39-1).
If the manufacturers test box is not being used, perform the following step.
- Remove the Engine Control Module (ECM) (J623) => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) 2 (G108) electrical harness connector terminals to the Engine Control Module (ECM) (J623) electrical harness connector terminals for resistance.
• Heated Oxygen Sensor (HO2S) (-G39-) (Bank 1, Sensor 1).
• Heated Oxygen Sensor (HO2S) (-G108-) (Bank 2, Sensor 1).
Specified value: 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.
If no malfunctions are found in wiring:
- Replace Heated Oxygen Sensor (HO2S) (-G139-) or Heated Oxygen Sensor (HO2S) (-G108-)
- 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 ] 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). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Assembly is performed in the reverse of the removal.
After 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 ] Monitors, Trips, Drive Cycles and Readiness Codes.