Left Hand Drive

O2 Sensor Cutaway View (Typical):

PURPOSE
The Powertrain Control Module (PCM) uses input from the heated oxygen sensor in the exhaust pipe to fine tune air/fuel mixture. This is done by varying injector pulse width (on time).

OPERATION
The oxygen sensor is a voltage generating device. A voltage signal (0-1 volt) is generated by comparing the difference in oxygen content between the exhaust gases and outside air. The higher the difference (rich mixture, low exhaust oxygen content) the higher the voltage generated by the oxygen sensor. Smaller differences (lean mixture, high exhaust oxygen content) result in a lower voltage being generated.

The oxygen sensor has a heating element that maintains proper oxygen sensor operating temperature at all times. This process allows the vehicle to enter closed loop at an earlier time and to remain in closed loop during the remainder of the operating cycle. The oxygen sensor heating element receives voltage from the fuel pump relay.

During CLOSED LOOP operation, the PCM monitors the signals it receives from the oxygen sensor, and other sensors, and uses these signals to adjust the injector pulse width according to the current driving condition.

During OPEN LOOP operation, the PCM ignores the oxygen sensor's signals, and other sensor's signals, and adjusts injector pulse widths according to preprogrammed specifications in the PCM.

CIRCUIT OPERATION
When the fuel pump relay contacts close, they connect circuits A14 and A141. Circuit A141 splices to supply voltage to the heated oxygen sensor.

Circuit K41 delivers the signal from the heated oxygen sensor to the Power train Control Module (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 side of the engine.