C121D Code: Meaning, Causes, and Symptoms | OBD2 Codes

C121D – Brake Pressure Sensor Circuit

 

C121D Possible Symptoms

 

Anti-Lock Brake System (ABS) Warning Light ON,Engine Light ON (or Service Engine Soon Warning Light)

 

C121D Possible Causes

 

Faulty Brake Master Cylinder,Faulty Brake Booster,Faulty Anti-Lock Brake System (ABS) Module,Anti-Lock Brake System (ABS) Module harness is open or shorted,Anti-Lock Brake System (ABS) Module circuit poor electrical connection

 

C121D Description

 

The Anti-Lock Brake System (ABS) Module monitors the Brake Pressure Sensor. The ABS Module sets the OBDII code when the Brake Pressure Sensor is not to factory specifications.