Oxygen Sensor Heater before Catalytic Converter, Checking
Oxygen Sensor Heater before Catalytic Converter, Checking
Oxygen Sensor (O2S) Heater (Z19), Checking
• Oxygen Sensor (O2S) Heater (Z19) is part of Heated Oxygen Sensor (HO2S) (G39) and cannot be replaced separately.
• When servicing electrical harness connector terminals for the Heated Oxygen Sensor (HO2S), use only gold-plated terminals.
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• Fuse (SB2) OK.
• Fuel Pump (FP) 2 Relay (J49) 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. Diagnostic Mode 09 - Read Vehicle Information.
Start diagnosis
- Remove the engine cover with air filter.
Checking internal resistance
- Disconnect the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector - 2 -.
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) terminals 3 to 4 for an open circuit.
Specified value: 2.5 to 10.0 ohms (at approx. 20° C)
If the specification was not obtained:
- Replace the 2- Heated Oxygen Sensor (HO2S) (G39) or the 1 Heated Oxygen Sensor (HO2S) 2 (G108).
If the specification was obtained:
Checking voltage supply
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) electrical harness connector terminal 4 to ground (GND) for voltage.
Specified value: Battery voltage.
If the specification was not obtained:
- Check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminal 4 to the Fuel Pump (FP) 2 Relay (J49) 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). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) electrical harness connector to the Engine Control Module (ECM) (J623) electrical harness connector T81 for resistance.
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. 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 Description ] Diagnostic Mode 09 - Read Vehicle Information.
- 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.
Final procedures
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 ] Engine.
End of diagnosis
Oxygen Sensor (O2S) 2 Heater (Z28), Checking
• Oxygen Sensor (O2S) 2 Heater (Z28) is part of Heated Oxygen Sensor (HO2S) 2 (G108) and cannot be replaced separately.
• When servicing electrical harness connector terminals for the Heated Oxygen Sensor (HO2S), use only gold-plated terminals.
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• Fuse (SB4) OK.
• Fuel Pump (FP) 2 Relay (J49) 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. Diagnostic Mode 09 - Read Vehicle Information.
Start diagnosis
- Remove the engine cover with air filter.
Checking internal resistance
- Disconnect the Heated Oxygen Sensor (HO2S) 2 (G108) electrical harness connector - 1 -.
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) 2 (G108) terminals 3 to 4 for resistance.
Specified value: 2.5 to 10.0 ohms (at approx. 20° C)
If the specification was not obtained:
- Replace the Heated Oxygen Sensor (HO2S) 2 (G108).
If the specification was obtained:
Checking voltage supply
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminal 4 to ground (GND) for voltage.
Specified value: Battery voltage.
If the specification was not obtained:
- Check the Heated Oxygen Sensor (HO2S) 2 (G108) electrical harness connector terminal 4 to the Fuel Pump (FP) 2 Relay (J49) 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). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) 2 (G108) electrical harness connector to the Engine Control Module (ECM) (J623) electrical harness connector T81 for resistance.
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. 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 Description ] Diagnostic Mode 09 - Read Vehicle Information.
- 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.
Final procedures
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 ] Engine.
End of diagnosis