A failed or intermittent Door Control Module A, often due to water intrusion or internal circuit board corrosion.; Damaged, chafed or corroded wiring in the door jamb boot where the harness flexes every time the door opens and closes.; Loose or corroded connector pins at the door module or at the body control module end of the network.; A blown fuse or poor ground connection that removes power from the door module without blowing the main network fuse.; A shorted or open communication bus wire (CAN, LIN or similar) between the door module and the rest of the network.; Another module on the same bus holding the network down and preventing Door Control Module A from communicating.; Low battery voltage or a weak charging system causing modules to drop offline intermittently.

DTC codes / U01xx · Lost communication with a control module / U0199

U0199Lost Communication With 'Door Control Module A'

Q: What does code U0199 mean?

Lost Communication With 'Door Control Module A'. U0199 means the module that supervises the vehicle's communication network has stopped hearing from Door Control Module A, which is the body computer responsible for one or more doors. The supervising module sets this code when the expected periodic messages from that door module fail to arrive for a calibrated period, not when a door simply fails to lock or a window stops working.

U0199 means the module that supervises the vehicle's communication network has stopped hearing from Door Control Module A, which is the body computer responsible for one or more doors. The supervising module sets this code when the expected periodic messages from that door module fail to arrive for a calibrated period, not when a door simply fails to lock or a window stops working.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

Often no symptoms besides the warning light, because the door module may still operate locally while only its network messages are missing.
One door's power lock, window, mirror or puddle lamp functions stop responding to commands from the master switch.
The interior dome light or door-ajar warning behaves erratically or stays on after the door is closed.
The key fob or central locking system fails to lock or unlock one specific door.
Multiple unrelated warning lights or network codes appear if the door module is dragging down the communication bus.
The vehicle may not sleep properly, leading to a parasitic battery drain overnight.

Common causes, most likely first

A failed or intermittent Door Control Module A, often due to water intrusion or internal circuit board corrosion.
Damaged, chafed or corroded wiring in the door jamb boot where the harness flexes every time the door opens and closes.
Loose or corroded connector pins at the door module or at the body control module end of the network.
A blown fuse or poor ground connection that removes power from the door module without blowing the main network fuse.
A shorted or open communication bus wire (CAN, LIN or similar) between the door module and the rest of the network.
Another module on the same bus holding the network down and preventing Door Control Module A from communicating.
Low battery voltage or a weak charging system causing modules to drop offline intermittently.

How to diagnose and fix it

Verify battery voltage and charging system output, then clear the code and confirm whether U0199 returns immediately or only after a drive cycle.
Inspect the door jamb wiring boot and the door module connector for chafed wires, green corrosion or pushed-out pins.
Check the fuse and ground for the affected door module with a test light or multimeter under load.
Measure communication bus resistance and voltage at the door module connector to confirm the bus is healthy and the module is being powered and grounded.
Substitute a known-good Door Control Module A or perform a module swap only after wiring and power checks pass, then relearn or configure the module if required.
If the module communicates but functions are dead, scan all modules for related codes and check for a network fault caused by another module on the same bus.
After repair, clear codes, cycle the ignition and operate every door function to confirm the code does not reset.

Door jamb wiring fails more often than the module

The flexible rubber boot between the door and body is the most common failure point for this code, and a visual check often misses a broken wire inside intact insulation.
A door module that still locks and unlocks the door locally can still set U0199 because the code only reports lost network messages, not lost local function.
Water intrusion into the door cavity from a blocked sunroof drain or failed vapor barrier frequently corrodes the module connector and mimics a failed module.
A weak battery or a module on the same bus that stays awake can prevent the door module from communicating, so the door module is often replaced unnecessarily.
On some vehicles the door module shares a bus with the seat or mirror module, so a fault in those components can set U0199 even though the door itself works.

Can I keep driving with U0199?

The vehicle is generally safe to drive because the door still opens and closes mechanically, but avoid relying on central locking or window operation for that door and do not leave the vehicle unlocked. Address the fault promptly if the battery drains overnight or if multiple network codes appear, because a dragging bus can affect other systems.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.