Oxygen Sensor

The oxygen sensor is installed in exhaust manifold. Output voltage of sensor varies with oxygen content of exhaust gases in exhaust gas stream. High output voltage to ECM signals that mixture is too rich; ECM issues lean command to duty cycle solenoid. Low output voltage to ECM signals that mixture is too lean; ECM issues rich command to duty cycle solenoid.

The ECM does not accept oxygen sensor information until sensor has warmed to about 600°F (316°C). Until oxygen sensor is fully operational, ECM remains in open loop mode of operation. When oxygen sensor becomes operational, ECM accepts information and relays corrected air/fuel ratio commands to duty cycle solenoid.