U0199 indicates that a network master (often the PCM or body‑control module) has lost communication with the door‑control module. The fault is set when the module does not respond on the controller‑area network (CAN) bus, usually because of wiring, connectors, power supply, or module failure. The MIL may illuminate and door‑related functions such as locks, windows, or mirrors may become inoperative.
Open, shorted, or corroded CAN bus wires or poor connections at the door module harness can prevent communication.
The module itself may have failed, preventing it from sending or responding to network messages.
A blown fuse, faulty relay, or broken power/ground circuits can leave the door module without the voltage needed to operate.
A short or excessive resistance on the bus, including damaged termination resistors, can disrupt communication for all modules.
A fault in another network node can flood the bus or pull signals low, making the door module unreachable.
Rarely, the controlling module may have an internal error that prevents it from recognizing the door module, but this is far less common than wiring or module issues.
The vehicle can usually be driven, but door‑related features such as locks, windows, or mirrors may be inoperative; have the problem investigated promptly to avoid being locked out or stranded.
No. While the PCM is listed as a possible cause, it is rarely at fault. Most cases involve wiring, connectors, power supply, or the door module itself.
In most situations replacing the PCM is unnecessary. The fault is usually in the door module wiring or the module itself; only after those are confirmed should a PCM issue be considered.
Checking power, ground, and CAN bus signals at the module connector will usually reveal a wiring issue; if those are good but the scan tool still shows no communication, the door module is likely faulty.