Oxygen Sensor (O2S) - Federal Emissions

Exhaust Oxygen Sensor (02):

PURPOSE:
The oxygen (O2) sensor measures the oxygen content of the exhaust. The ECM monitors the sensor to maintain air/fuel mixture of 14.7 to 1.

OPERATION:
The oxygen sensor monitors atmospheric air versus exhaust gas oxygen content to produce a voltage output. This voltage ranges from approximately 0.1 volt (high oxygen-lean mixture) to 0.9 volt (low oxygen-rich mixture). By monitoring the oxygen sensor output voltage, the computer can determine the amount of oxygen in the exhaust gas and adjust the air/fuel mixture accordingly, this is known as "CLOSED LOOP" operation.

When the sensor is cold it is like an open circuit and produces no voltage below 600°F (315°C). An open sensor circuit or cold sensor causes "OPEN LOOP" operation.

LOCATION:
Exhaust Manifold