Oxygen Sensor Test

1. Apply parking brake, start engine and increase speed to 2000 RPM on front wheel drive models and 1500 RPM on rear wheel drive models. Make sure carburetor switch is not grounded.
2. Connect voltmeter to green solenoid output wire going to carburetor.
3. To perform full rich test, hold choke blades closed. During the next 10 seconds, voltage should decrease to 5 volts or less and remain there. If engine does not respond, proceed to step 4.
4. To perform full lean test, disconnect PCV system at vacuum source. During the next 10 seconds, voltage should increase to at least 9 volts and remain there until vacuum hose is reconnected.
5. If sensor fails tests in steps 3 and 4, replace. Reconnect all hoses and wires.