Oxygen Sensor Testing

1. The output of the oxygen sensor can be checked with a digital voltmeter having a minimum input resistance (impedance) of 1 megohm (1 million ohms).
2. Proceed as follows:

Fig. 210 Disconnecting Oxygen Sensor Harness:

a. Disconnect the oxygen sensor from the vehicle harness.

O2 Sensor:

b. Insert a jumper with exposed wire between the sensor and the harness to ease probing, and reconnect connector.
c. Set the voltmeter to the 2 volt scale.
d. Connect the positive lead of the voltmeter to the jumper and the negative lead to vehicle ground.
e. Start the engine and run at 2500 rpm for 2 minutes or until the engine has gone into "closed loop" operation.
f. The meter should move between approx. 0.50 and 0.80 volts.