Generic Scan Tool

Oxygen Sensor Heater before Catalytic Converter, Checking

• When servicing terminals in harness connector of Oxygen Sensor (O2S) Heater (Z19), use only gold-plated terminals.

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Oxygen Sensor (O2S) Heater (Z19) 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 (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

Procedure

- Remove the engine cover with air filter. Refer to Fuel Injection and Ignition Repair Information.





Checking internal resistance

- Disconnect the Oxygen Sensor (O2S) Heater (Z19 ) electrical harness connector - 5 -.





- Using a multimeter, check the Oxygen Sensor (O2S) Heater (Z19) terminals 3+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 Oxygen Sensor (O2S) Heater (Z19). Refer to Fuel Injection and Ignition Repair Information.

If the specification is obtained:

Checking voltage supply

- Using a multimeter, check the Oxygen Sensor (O2S) Heater (Z19) electrical harness connector terminal 4 to the Fuel Pump (FP) Relay (J17) terminal 2 for voltage.









Specified value: Battery voltage.

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, lose 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. Refer to Fuel Injection and Ignition Repair Information.

If the manufacturers test box is not being used. Perform the following step.

- Remove the Motronic Engine Control Module (ECM) ( J220). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a multimeter, check the Oxygen Sensor (O2S) Heater (Z19) electrical harness connector terminal 4 to the Motronic Engine Control Module (ECM) ( J220) electrical harness connector terminal 5 for an open circuit.









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, lose 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:

- Replace the Motronic Engine Control Module (ECM) (J220). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Install the engine cover with air filter. Refer to Fuel Injection and Ignition Repair Information.

Final procedures

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 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 ] Readiness Code.

- End of diagnosis.