Heated Oxygen Sensor (HO2S)

HO2S monitors oxygen content of exhaust gases. This electrically heated O2 sensor is mounted in the exhaust manifold or pipe. When HO2S is at operating temperature, a voltage signal is produced, which varies according to oxygen content of exhaust gases. Signal is transmitted to the PCM, and is translated into a rich or lean mixture signal.

HO2S uses a built-in heating circuit. The heating circuit is used to bring the HO2S up to operating temperature, enabling faster conversion to closed-loop operation. The 2.5L is equipped with 2 sensors, one for each exhaust bank.