DTC P00D1-00: HO2S Heater Control Circuit Range/Performance Bank 1/Sensor 1: General Description

Heated Oxygen Sensor (HO2S), consisting of zirconium and alumina, is installed on both upstream and downstream of the catalytic converter to detect the air/fuel ratio and send it to the PCM. The sensor must be heated in order to operate properly. To keep it heated, the sensor has a heater which is controlled by the PCM via a duty cycle signal. When the exhaust gas temperature is lower than the specified value, the heater warms up the sensor tip.