### Oxygen Sensor

#### OPERATION

The exhaust oxygen sensor or O2S, is mounted in the exhaust stream where it monitors oxygen content in the exhaust gas. The oxygen content in the exhaust is a measure of the air/fuel mixture going into the engine. The oxygen in the exhaust reacts with the oxygen sensor to produce a voltage which is read by the ECM.

There are two types of oxygen sensors used in these vehicles. They are the single wire oxygen sensor (02S) and the heated oxygen sensor (H02S). The oxygen sensor is a spark plug shaped device that is screwed into the exhaust pipes. It monitors the oxygen content of the exhaust gases and sends a voltage signal to the Electronic Control Module (ECM). The ECM monitors this voltage and, depending on the value of the received signal, issues a command to the mixture control solenoid on the carburetor to adjust for rich or lean conditions.

The heated oxygen sensor has a heating element incorporated into the sensor to aid in the warm up to the proper operating temperature and to maintain that temperature.

The proper operation of the oxygen sensor depends upon four basic conditions:

- Good electrical connections. Since the sensor generates low currents, good clean electrical connections at the sensor are a must.
- Outside air supply. Air must circulate to the internal portion of the sensor. When servicing the sensor, do not restrict the air passages.
- Proper operating temperatures. The ECM will not recognize the sensor's signals until the sensor reaches approximately 600°F (316°C).
- Non-leaded fuel. The use of leaded gasoline will damage the sensor very quickly.