The U0502 code indicates that a module on the vehicle's network has received corrupted, implausible, or invalid data from Door Control Module C. This usually points to a communication fault on the data bus, a wiring issue in the door harness, or a failure within the door module itself, rather than a problem with the module receiving the data.
Broken, chafed, or corroded wires in the door jamb harness or at the module connector disrupt the data signal.
The module itself has an internal fault causing it to transmit garbled or out-of-range data.
Insufficient power or a bad ground connection to the door module can cause it to output invalid data.
A short or open circuit on the CAN or LIN bus corrupts the data packets being transmitted.
A recently replaced or reprogrammed module has incorrect software, causing data translation errors.
The module receiving the data is misinterpreting valid signals, though this is extremely rare.
Generally yes, but door functions like locks, windows, and mirrors may be inoperative, which can be a safety or security concern.
Almost never. While the PCM may be the module receiving the invalid data, the actual fault lies in the Door Control Module C, the wiring, or the network. Replacing the PCM is rarely the correct fix for this code.
Manufacturers assign letters or numbers to specific doors differently. You will need a model-specific service manual to identify whether 'C' refers to the driver rear, passenger front, or another door on your vehicle.
The most frequent cause is wiring damage inside the rubber boot between the door and the car body, where constant flexing eventually breaks the data or power wires.