Oxygen Sensor: Description and Operation

LOCATION
Sensor threaded into exhaust manifold.

SENSOR PURPOSE
Powertrain Control Module (PCM) uses input to determine whether to enrich or lean air/fuel mixture, during closed loop operation.

SENSOR OPERATION
Sensor, generates a voltage between 0 and 1.0 volts dependant on difference between unused oxygen in exhaust gas and oxygen outside exhaust system. SEE Specifications.

HEATER PURPOSE
Vehicle enters CLOSED LOOP faster, (because sensor reaches operating temperature sooner).

Allows CLOSED LOOP operation during extended idle, (because heater maintains correct operating temperature).

NOTE: The following information is intended to be used in conjunction with the electrical diagrams.

CIRCUIT OPERATION
When the Powertrain Control Module (PCM) grounds the Automatic Shut Down (ASD) relay, the contacts close and connect circuits A14 and A142. Circuit A142 supplies battery voltage to the heated oxygen sensor. A 30 amp fuse in cavity D of the PDC protects the A14 and A142 circuits.

Circuit K41 delivers the signal from the heated oxygen sensor to the PCM. Circuit K41 connects to cavity 41 of the PCM.

The PCM provides a ground for the heated oxygen sensor signal (circuit K41) through circuit K4. Circuit K4 connects to cavity 4 of the PCM connector.

- Circuit Z12 provides a ground for the heater circuit in the sensor.
- Circuit Z12 terminates at the right rear of the cylinder head.