Oxygen Sensor

Sensor is mounted in engine exhaust stream. It supplies a low voltage (under 1/2 volt) when fuel mixture is lean (too much oxygen) and a higher voltage (up to 1 volt) when fuel mixture is rich (not enough oxygen). Oxygen sensor must be over 600°F (300°C) to function properly.

Oxygen sensor measures quantity of oxygen only. On some occasions, the oxygen sensor may cool off during idle, causing CCC system to go into open loop mode. Running the engine at fast idle will warm up oxygen sensor.

Oxygen sensor voltage output should not be measured. Current drain from voltmeter could permanently damage sensor, shift sensor calibration range and/or render sensor unusable. Do not connect jumper wire, test leads or other electrical connectors to sensor. Use these devices on ECM side of harness only, after disconnecting harness from sensor.