Oxygen Sensor: Description and Operation

Oxygen Sensor and Output Chart:

PURPOSE
The ECU uses the O2 signal to correct fuel mixture by changing injector duration as required.

LOCATION
The oxygen sensor (O2) is mounted to the exhaust manifold or pipe with the sensor end extending into the exhaust stream.

CONSTRUCTION
The sensor uses zirconia and platinum to compare exhaust oxygen content with that of the outside air.

OPERATION
When heated by the combination of its internal heater and exhaust gases, the sensor supplies a low voltage signal (0 - 1 volt) to the ECM. When the engine is running rich, the oxygen differential is relatively high so signal voltage increases. When a lean condition occurs the difference in oxygen content is much lower causing a lower voltage signal to be produced.