CAN network

U0200 — Lost Communication with Door Control Module A

Severity: medium Safe to drive

What U0200 means

Another control unit stopped receiving messages from door control module A over the CAN bus. This module normally runs the window, lock and mirror functions on its door and shares data with the body control system. When it goes silent, those functions become unavailable and the code is stored.

Symptoms

  • Power window on that door does not work
  • Mirror adjustment is dead
  • Door lock does not respond
  • Several warning lamps may come on
  • Functions handled by the door module are unavailable

Possible causes

  1. Failed door module
  2. Fatigued or broken wires in the door jamb harness
  3. Water in the door and corroded contacts
  4. CAN bus wiring fault (open, short, chafed harness)
  5. Another faulty module loading the bus
  6. Corroded connector or terminals
  7. Power supply or ground fault at the door module

How to diagnose

  1. Run a full-module scan to see which modules are not communicating
  2. Look for other U-codes or codes related to the same door
  3. Check CAN bus resistance and voltages at the diagnostic connector
  4. Inspect the harness in the door jamb for breaks and chafing
  5. Check the door module connector for moisture, corrosion and bent pins
  6. Measure power supply and ground at the module connector
  7. Disconnect suspect modules one at a time only with a documented procedure
  8. If wiring and power are good, test or replace the door module and program it as required

Common fixes

  • Repair the damaged door jamb harness
  • Clean or replace corroded connectors and terminals
  • Fix the source of water leaking into the door
  • Restore power or ground to the module
  • Replace the door module and program it if needed

Questions and answers

What does U0200 mean?

It means a control unit lost communication with door control module A. The module is not answering on the CAN bus, so features on that door may stop working.

Can I drive with code U0200?

Usually yes, because the engine and brakes are not affected. A lock or window that will not work can still be inconvenient or a security risk.

What should I check first?

Inspect the harness in the door jamb and the door module connector, then check the module's power and ground. Broken wires and water damage are common causes.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.