Circuit Description

Powertrain Control Module (PCM) supplies about 450 mV to Heated Oxygen Sensor 1 (HO2S 1). The HO2S 1 supplies a varying voltage from about 800 mV when exhaust is rich to about 50 mV 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 that HO2S 1 voltage remains at or near 450 mV for an extended period, DTC will set.

For duplication of DTC, ensure engine is running, and no active fuel trim, fuel injector circuit, misfire, EVAP system, EGR system, TP, IAT, MAP, ECT, CKP, or MAF sensor DTCs are present.