Oxygen Sensor: Description and Operation

Oxygen Sensor:

PURPOSE
Measures O2 content in exhaust gas.

LOCATION
In the exhaust manifold.

OPERATION
The heated oxygen sensor (HO2S) is the primary input to the fuel delivery system. The engine control module (ECM) monitors the HO2S voltage, when the system is in closed loop operation. When the voltage reading is high the air/fuel mixture is rich, and when the voltage reading is low the air/fuel mixture is lean. Under normal operating conditions, the voltage reading will constantly fluctuate.