Circuit Description

Powertrain Control Module (PCM) supplies about .45 volt to Oxygen Sensor 1 (O2S 1). The O2S 1 supplies a varying voltage from about one volt when exhaust is rich to about .10 volt when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects O2S 1 voltage remains at or near .45 volt for an extended period, DTC will set.