Fault-code directory · BCM and body-electronics assessment
When the window, mirror and lock on one door stop working together, a shared supply or communication problem is worth investigating. Replacing each mechanism separately may miss the common cause. The pattern of affected functions helps define the first checks.
Codes covered
U0199 · U0200 · U0201 · U0202
These codes refer to lost communication with door control modules A to D where fitted. The letters must be mapped using vehicle information; they are not a universal left-front to right-rear order. A missing module in the scan does not prove that the module itself has failed.
Confirm the full description, suffix and reporting module for your vehicle. These are diagnostic starting points, not a parts replacement list.
Evidence that helps narrow the fault
- List which functions work from the local door switch and which work from the main controls. Include whether opening the door changes the symptoms.
- Inspect the relevant power and ground paths and the flexing harness route using the correct procedure. Movement-related faults may not appear in a stationary continuity check.
- Review water exposure and recent door, mirror or speaker work. Keep the full scan to show whether other devices on the same network are also unavailable.
Choosing the next repair step
The repair may be in the hinge-area harness, a connector, a supply or the door electronics. A replacement module may also require compatible configuration. If windows cannot be safely operated or the vehicle cannot be secured, mention that when arranging assessment so the practical problem is clear.
Does a working door light prove the door module has power?
Not necessarily. Different functions may use different feeds or paths. Test the actual module supply and ground rather than assuming that one working lamp proves every circuit is healthy.
Talk through the fault with AXION
Send the make, model, year, full scan report and a short description of when the fault happens. Include recent repairs or programming attempts. If you do not have a scan, describe the symptoms in your own words.
Workshop assessments are arranged by appointment in Didcot, Oxfordshire. UK-wide postal module testing and remote support are available for suitable work after compatibility and scope are agreed. Please contact us before removing or posting a module.
Assessment options and appointments · Garage and trade support
Related reading
- U0422 when other modules reject body-control data
- U0423 and instrument-cluster data warnings after module work
Reference for generic code terminology: Snap-on diagnostic code reference. Use the manufacturer’s current service information for the actual vehicle and test procedure. This article provides general diagnostic guidance and is not a report of a particular customer repair.