Oxygen Sensor
The oxygen sensor is mounted in the exhaust manifold. This sensor is similar to a small battery. The voltage output of the sensor indicates to the ECM the amount of oxygen in the exhaust gases. The ECM corrects the air/fuel ratio according to signals received by the oxygen sensor only when the system is operating in closed loop.
CAUTION:
No attempt should be made to measure oxygen sensor voltage output. Current drain of conventional voltmeter could permanently damage sensor, shift sensor calibration range and/or render sensor unserviceable. DO NOT
connect jumper wire, test leads or other electrical connectors to sensor.