The B1503 Code has a meaning and this code appears for the diagnosis of the engine. This error code also appears for other cars and meaning can be different. To get the meaning of the code, it is necessary to know the model and manufacturer. The B1503 Code has come for the body problem of the engine and it may not necessary to change any component of the engine. The dictionary meaning of the code is B for Body Code Problem is antilock brake system, electronic suspension and steering systems. 1 for MFG – Manufacturer Specific. 5 for Computer and Auxiliary Outputs. 0 for IC Circuit High Voltage and 3 for Transmission Control Module Reprogrammable Memory.