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Oxygen Sensor Operation:

Two oxygen sensors, a main and a sub, measure the oxygen content in the exhaust and send a voltage signal to the ECM.

Each sensor consists of a steel housing, sensor tip and its protective sleeve. The sensor tip itself is made from a platinum covered zirconium-oxide pipe.


This sensor produces a measureable voltage by comparing the amount of oxygen in the exhaust gas with the amount in the ambient air.

The sensor operates only within a certain temperature range of approx. 545 - 1530°F (285 - 850°C).

The exhaust gases reach the outer surface of the oxygen sensor tip via the openings in the protective sleeve. Ambient air reaches the sensor's inner surface via channels. The differance in oxygen content produces a voltage read by the ECM.

The sub-oxygen sensor functions primarily as a diagnostic aid for the catalyst. The ECM compares sensor outputs to determine if the catalyst is functioning properly.