Electrically Heated O2 Sensor
Electrically heated O2 sensor is used on 4.3L engine. This sensor is energized by fuel pump relay and remains on as long as engine is running. Failure of heating element, power feed or ground circuit may cause Code 13 to be set at idle or low RPM.
NOTE:
No attempt should be made to measure O2 sensor voltage output. Current drain of conventional voltmeter could permanently damage sensor, shift sensor calibration and/or render sensor unusable. DO NOT
connect jumper wire, test leads or other electrical connectors to sensor.