B1125 The door multiplex control unit lost the driver side power window motor A pulse signal

What does B1125 mean on a Honda?

B1125. The door multiplex control unit lost the driver side power window motor A pulse signal. The window may stop or reverse part way in auto travel. This Honda-enhanced code applies to Honda and Acura models that use this code.

Common causes of B1125

• Faulty Driver Side Power Window Motor 'A'
• Driver Side Power Window Motor 'A' harness is open or shorted
• Driver Side Power Window Motor 'A' circuit poor electrical connection
• Faulty Door Multiplex Control Unit
• Water intrusion in the door connector

How to fix B1125

1. Confirm the code with a scan tool and operate the window from both switches
2. Inspect the door wiring harness and the window motor connector for damage or moisture
3. Test the window motor and position circuit against the service manual
4. Repair any damaged wiring in the door before replacing the motor
5. Replace the motor or master switch only after tests prove it failed

Sources and review

• Last updated 2026-09-26.