General Information: General Description

The Heated Oxygen Sensor (HO2S) detects the oxygen content in the exhaust gas to control emissions; It is mounted on both the upstream and downstream side of the catalytic converter. The upstream HO2S signal is used to control the air/fuel ratio (closed loop fuel control), and the downstream HO2S signal is used to monitor the catalyst for proper operation. The HO2S requires a minimum temperature to operate properly and to provide a closed loop fuel control system. The HO2S contains a heater element to reduce its warm-up time. The PCM interprets a high oxygen content as "LEAN" condition and low oxygen content as "RICH" condition.