Heated Oxygen Sensor (HO2S)

All models are equipped with 2 HO2S sensors. They are located in exhaust before and after catalytic converter. These sensors measure quantity of oxygen left in exhaust gas after combustion. ECM uses signal from HO2S in front of converter to adjust air/fuel mixture. HO2S behind catalytic converter is used to monitor converter efficiency by comparing readings from both sensors. If voltage signals from both sensors are the same, ECM sets a DTC and turns on CHECK ENGINE light, due to the fact that catalytic converter is not affecting oxygen content of exhaust. The electric heating element built into each sensor provides improved cold engine driveability, and ensures that HO2S operating temperature is maintained at idle.