Oxygen Sensor
Oxygen sensor is mounted in exhaust manifold, directly behind cross-over pipe. This sensor is similar to a small battery. Voltage output of sensor indicates to ECM the amount of oxygen in exhaust gases. ECM corrects air/fuel ratio (according to signals received by oxygen sensor) only when 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. DO NOT
connect jumper wire, test leads or other electrical connectors to sensor.