The Oxygen (O2) Sensor provides the Powertrain Control Module (PCM) with information for air/fuel ratio control. The output of this sensor regulates the deviation from the stoichiometric air/fuel ratio. It also controls the injection timing. If the O2 Sensor does not work properly, the vehicle’s computer cannot accurately make the required adjustments to the air/fuel mixture.
DTC P2238 OBDII is set next to the Check Engine light when the PCM detects that the positive current of the Oxygen Sensor 1 on bank 1 is out of range or below the manufacturer’s set value.