Oxygen Sensor: Description and Operation

The oxygen sensor--mounted in the exhaust system ahead of the catalytic converter--provides a varying DC voltage to the ECM representing the oxygen content of the exhaust gas.
- When the fuel mixture is lean sensor voltage is low--under 0.2 volts--.
- When the fuel mixture is rich sensor voltage is high--up to 1 volt--.

The ECM uses these signals to control Mixture Control (MC) solenoid operation.

NOTE: Voltage signals are not supplied by the sensor until exhaust temperature reaches 600° F.