Checking Oxygen Sensor Heating

OXYGEN SENSOR HEATER, CHECKING:

NOTE:
- Z29 = Oxygen Sensor (02S) heater, bank 1.
- Z3O = Oxygen Sensor (02S) heater, bank 2.

- Disconnect heated oxygen sensor harness connector.



- Switch multimeter (Fluke 83 or equivalent) to 20 volt range and connect between terminals 1 (B+) and 2 (GND).
- Start engine and let idle.

Specified Value: approx. 12 to 14 V.

If the specified value is not obtained:
- Check oxygen sensor heater fuse.
- Check fuel pump relay.
- Check wiring for continuity between terminal 1 and fuse in fuse holder using wiring diagram, if necessary check terminal assignments.

Specified Value: max. 1 Ohms.

- Check wiring for continuity between terminals 2 and 8 on ECM connector E.

Specified Value: max. 1 Ohms.

- Check wiring for continuity between terminals 2 and 3 of ECM connector E (02S heater -Z30-).

Specified Value: max. 1 Ohms.

If the specified value is obtained:



- Switch multimeter (Fluke 83 or equivalent) to measure resistance Ohms and connect between terminals 1 and 2.

Specified Value (room temperature): approx. 2 to 5 Ohms.

NOTE: With small increases in temperature, resistance will increase sharply.

If the specified value is not obtained:
- Replace heated oxygen sensor.