See Figures 1 and 2
The oxygen sensor supplies the computer with a signal which indicates a rich or lean condition during engine operation. The input information assists the computer in determining the proper air/fuel ratio. A low voltage signal from the sensor indicates too much oxygen in the exhaust (lean condition) and, conversely, a high voltage signal indicates too little oxygen in the exhaust (rich condition).
The oxygen sensors are threaded into the exhaust manifold and/or exhaust pipes on all vehicles. Heated oxygen sensors are used on some later models to allow the engine to reach the closed loop faster.
- With the oxygen sensor connected and the engine running, measure the voltage between the oxygen sensor connector and ground with a Digital Volt-Ohmmeter (DVOM). If the voltage readings are swinging rapidly between 0.01-1.1 volts, the sensor is probably okay.
- Disconnect the HO2S.
- Measure the resistance between PWR and GND terminals of the sensor. If the reading is approximately 6 ohms at 68°F (20°C). the sensor's heater element is in good condition.
- With the HO2S connected and engine running, measure the voltage with a Digital Volt-Ohmmeter (DVOM) between terminals HO2S and SIG RTN (GND) of the oxygen sensor connector. If the voltage readings are swinging rapidly between 0.01-1.1 volts, the sensor is probably okay.
REMOVAL & INSTALLATION
See Figures 3 and 4
- Disconnect the negative battery cable.
- Raise and safely support the vehicle on jackstands.
- Disconnect the HO2S from the engine control sensor wiring.
If excessive force is needed to remove the sensors, lubricate the sensor with penetrating oil prior to removal.
- Remove the sensors with a sensor removal tool, such as Ford Tool T94P-9472-A.
- Install the sensor in the mounting boss, then tighten it to 27-33 ft. lbs. (37-1 Nm).
- Reattach the sensor electrical wiring connector to the engine wiring harness.
- Lower the vehicle.
- Connect the negative battery cable.