Ford P1138 OBD-II Trouble Code Definition: P1138 Lack Of HO2S12 Switch – Sensor Indicates Rich P1138 Ford OBD-II Trouble CodeDescription: Symptoms – Engine Light ON (or Service Engine Soon Warning Light) P1138 OBD Code Description Lack Of HO2S12 Switch – Sensor Indicates Rich is one of the definitions for the P1138; however your vehicle’s manufacturer may […]