Oxygen (O2) Sensor
- Disconnect 2-wire O2 sensor connector. Measure resistance between the 2 White wires. Resistance should be about 4 ohms.
- Set voltmeter to 2-volt DC scale. Connect voltmeter leads between Black sensor wire and ground. Start engine. Voltmeter reading should vary between 100-900 mV, as the sensor temperature increases and the air/fuel mixture changes. Replace O2 sensor is resistance is not as specified or sensor reaction time is too slow.