B138A Code: Meaning, Causes, and Symptoms | OBD2 Codes

B138A – Control Module Voltage Reference Output Circuit


B138A Possible Symptoms


Engine Light ON (or Service Engine Soon Warning Light)


B138A Possible Causes


Faulty Rear Parking Assist Alarm Sensor,Rear Parking Assist Alarm Sensor harness is open or shorted,Rear Parking Assist Alarm Sensor circuit poor electrical connection,Faulty Parking Assist Control Module


B138A Description


The object sensors are 3-wire sensors that are used to determine the distance between the vehicle and an object of interest. The Parking Assist Control Module supplies 8 V to the object sensors via the 8 V reference circuit and provides ground via the low reference circuit. The Parking Assist Control Module triggers the sensors in a sequential loop. After each sensor transmits, the Parking Assist Control Module uses the sensor echo received through the signal circuit to calculate the distance and position of an object.