Faulty Heated Oxygen Sensor (HO2S)
Heated Oxygen Sensor (HO2S) harness is open or shorted
Heated Oxygen Sensor (HO2S) circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
A resistor is installed in the Universal Heated Oxygen Sensor (HO2S) connector for part to part variance. The Powertrain Control Module (PCM) determines the value of this resistor by taking multiple measurements of the resistor during each ignition ON event. The PCM uses this value in order to compensate for the variance in the pumping current signal. The test fails if the PCM determines the resistance value is too high.