Oxygen (O2) Sensor

Mounted in the exhaust manifold, the O2 sensor monitiors the amount of oxygen in the exhaust stream. The sensor generates a weak voltage which varies with exhaust gas oxygen content.

Increased oxygen content creates a lean mixture, resulting in a low output voltage. Decreased oxygen content creates a richer mixture, resulting in a higher output voltage. ECM monitiors these voltages to determine correct air/fuel ratio.