Oxygen Sensor O2S Heater Before Three Way Catalytic Converter, Checking

Oxygen Sensor O2S Heater Before Three Way Catalytic Converter, Checking

Observe all safety precautions: => [ Safety Precautions ] Safety Precautions

View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

• Use only gold-plated terminals when servicing terminals in the electrical harness connector of the Heated Oxygen Sensor (HO2S) (G39) and Oxygen Sensor (O2S) Heater (Z19).

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Oxygen Sensor (O2S) Heater (Z19) fuse OK.

• The Heated Oxygen Sensor (HO2S) (G39) before catalytic converter OK. Refer to=> [ Heated Oxygen Sensor HO2S Before Three Way Catalytic Converter, Checking ] Heated Oxygen Sensor HO2S Before Three Way Catalytic Converter, Checking.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Exhaust system between catalytic converter and cylinder head properly sealed.

• Coolant Temperature at least 80 °C.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Start diagnosis

• For connector location, removal and installation procedures. Refer to the appropriate service manual.

- Remove the engine cover. Refer to the appropriate service manual.






- Disconnect the connector -1- from the Mass airflow sensor (G70) , and remove the Air Filter Housing. Refer to appropriate service manual.






Checking primary voltage

- Disconnect the Oxygen Sensor (O2S) Heater (Z19) electrical harness connector - 3 -.






Checking internal resistance






- Using a Multimeter, check the Oxygen Sensor (O2S) Heater (Z19) terminals 3 to 4 for resistance.

Specified value: 2.5 to 10.0 ohms (at approx. 20° C)

If the specified value was Not obtained:

- Replace the Oxygen Sensor (O2S) Heater (Z19). Refer to the appropriate service manual.

- Go to Final procedures

If the specified value was obtained:

Checking voltage supply

- Switch the ignition ON.

- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminal 4 to Ground (GND) for voltage.











- Switch the ignition OFF.

Specified value: Battery voltage.

If the specified value was Not obtained:

- Check the Oxygen sensor heater (Z19) electrical harness connector T6ab terminal 4 to Fuse SB 10 in Fuse Panel B Connector or an open circuit, a short circuit to each other or Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

- Repair the circuit and replace any open fuses.

- Go to Final procedures

If the specified value was obtained:

Checking Ground (GND) activation

- Remove the Engine Control Module (ECM) (J623). Refer to the appropriate service manual.

- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminal 3 to the Engine Control Module (ECM) (J623) electrical harness connector T94 for resistance.











Specified value: 1.5 ohms max.

If the specified value was Not obtained:

- Check the wiring for a short circuit to each other, Battery voltage, and Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

- Go to Final procedures

If the specified value was obtained:

- Replace the Engine Control Module (ECM) (J623). Refer to the appropriate service manual.

Final procedures

- Reinstall the engine covers, and Air Filter Housing, if necessary. Refer to the appropriate service manual.

- For connector location, removal and installation procedures. Refer to the appropriate service manual.

- After the 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 Modes 01 - 0A.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 0A.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Programming and Relearning