Oxygen Sensor: Testing and Inspection

Oxygen Sensor Inspection

1. Warm up the engine to normal operating temperature and run at idle.





2. Using a volt meter, measure the voltage at PCM terminals C254-2 (front sensor) and C254-10 (rear sensor).
3. increase and decrease the engine speed suddenly several times.
4. Verify that when the speed is increased, the meter reads 0.5 1.0V (both terminals), and when the speed is decreased it reads 0 - 0.5V (both terminals).
5. If not as specified, repeat the voltage check at the suspected faulty heated oxygen sensor.
6. if still not as specified, replace the heated oxygen sensor.

Oxygen Sensor Heater Circuit Inspection

1. Ensure tat the ignition switch is OFF.
2. Disconnect the heated oxygen sensor connector from the wire harness.





3. Connect an ohmmeter between terminals 1 and 3 of the connector and measure the resistance.

Resistance: Approximately 6ohms 68°F (20°C)

4. If not as specified, replace the heated oxygen sensor (see below).
5. Also check wire hamess for continuity.
1.8 Liter BP DOHC: Between pin 4 in C258 and pin 14 in C254.
6. If continuity is not correct, check wiring for opens.