Oxygen Sensor (O2S) Heater Z19 Before Catalytic Converter, Checking

Oxygen Sensor (O2S) Heater Z19 Before Catalytic Converter, Checking

NOTE: 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.

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 degrees C)

If the specification was not obtained:
- Replace the Oxygen Sensor (O2S) Heater Z19.

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.

Oxygen Sensor (O2S) Heater Fuel Pump (FP) Relay J17
Z19 electrical harness electrical harness connector
connector terminal terminal
4 2

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.

If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220.







- 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.

Oxygen Sensor (O2S) Heater Motronic Engine Control Module
Z19 electrical harness (ECM) J220 electrical connector
connector test terminal box socket
4 5

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.
- Install the engine cover with air filter.

Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code.

- End of diagnosis.