California

Oxygen Sensor Circuit:

To test either Oxygen Sensor, located near the catalytic converter, proceed as follows.

O2 SENSOR TEST
1. Start and warm the engine until the coolant temperature exceeds 80~C (176~F).
2. Connect a volt meter with at least 10 megaohm resistance between sensor terminals 1 and 3 (do not disconnect the connector).
3. Race the engine repeatedly and measure the output voltage of the oxygen sensor.

Voltage:
Should vary between between 400 mV or lower and 600mV.

4. Faulty results in the above test may be caused by:
a. Engine mechanical problems
b. Open or shorted wiring harness
c. Fuel pressure
d. Fuel mixture
5. Use a scan tool to check the oxygen sensor performance as compared to the measured voltages.
6. Perform all tests before replacing the sensor.

O2 SENSOR HEATER TEST
1. Disconnect the front oxygen sensor connector.
2. Check for continuity between terminals 2 and 4.

Continuity:
Approx. 20 ohms at 68°F

3. If there is no continuity, replace the front oxygen sensor.