Circuit Description

Oxygen sensor responds to oxygen content in exhaust manifold. Sensor voltage is read by the PCM to determine a rich/lean O2S1 signal used to adjust injector pulse width. Normal sensor reading will fluctuate between 10-999 mV. DTC will set if ratio of O2S1 lean-to-rich average time to rich-to-lean average is not within 0.6-2.8 within a 100 seconds test when engine speed is between 1500-3000 RPM, loop status is closed, calculated airflow is greater than 7 gm/s, commanded A/F ratio is 14.7:1, no CAM, CKP, ECT, EGR, EVAP, fuel trim, IAT, MAP, misfire, O2S1, system voltage or TP sensor DTCs not set.