Oxygen Sensor: Testing and Inspection

Voltmeter:

Connector View:

INSPECTION
1. Warm up the engine to normal operating temperature and run at idle.
2. Using a volt meter, measure the voltage of ECM terminals C249-20.
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 and when the speed is decreased it reads 0 - 0.5V.
5. If not as specified, repeat the voltage check at the suspected faulty heated oxygen sensor.
6. It still not as specified, replace the heated oxygen sensor.

SENSOR HEATER
1. Ensure that the ignition switch is OFF.
2. Disconnect the heated oxygen sensor connector from the wire harness.
3. Connect an ohmmeter between terminals 2 and 3 of the connector and measure the resistance.

Resistance: Approximately 13 ohms AT 68°F (20°C)]

4. If not as specified, replace the heated oxygen sensor.