Oxygen Sensor Heater Bank 1 Sensor 1, Checking
Diagnostic Procedures
Oxygen Sensor Heater Bank 1 Sensor 1, Checking
• Oxygen Sensor Heater Bank 1 Sensor 1 (Z19) is part of HO2S Oxygen Sensor Bank 1 Sensor 1 (G39) and cannot be serviced separately.
• When servicing terminals in the electrical harness connector of HO2S Oxygen Sensor Bank 1 Sensor 1 (G39), use only gold-plated terminals.
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• Fuse (SB33) fuse 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 connections between engine/transmission/chassis OK.
• Ignition switched off.
• The voltage for the Oxygen Sensor Heater Bank 1 Sensor 1 (Z19) is supplied by the Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670).
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.
Start diagnosis
- Disconnect the HO2S Oxygen Sensor Bank 1 Sensor 1 (G39) electrical harness connector.
Checking internal resistance
- Using a multimeter, check the Oxygen Sensor Heater Bank 1 Sensor 1 (Z19) 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 HO2S Oxygen Sensor Bank 1 Sensor 1 (G39). Refer to the Repair Information.
If the specification was obtained:
Checking voltage supply
Start the engine.
- Using a multimeter, check the Oxygen Sensor Heater Bank 1 Sensor 1 (Z19) electrical harness connector terminal to ground for voltage.
Specified value: above 9.5 V.
Switch the engine off.
If the specification was not obtained:
- Check the HO2S Oxygen Sensor Bank 1 Sensor 1 (G39) electrical harness connector terminal 4 to fuse 33 in Fuse Panel B for high resistance, a short to ground, or an open circuit.
- 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 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 HO2S Oxygen Sensor Bank 1 Sensor 1 (G39) electrical harness connector to the Engine Control Module (ECM) (J623) electrical harness connector T94 terminal for resistance.
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 ] Monitors, Trips, Drive Cycles and Readiness Codes.
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 ] Monitors, Trips, Drive Cycles and Readiness Codes.