What causes B1140 on a Honda?

Faulty Power Window Master Switch Power Window Master Switch harness is open or shorted Power Window Master Switch circuit poor electrical connection Faulty Door Multiplex Control Unit Water intrusion in the door connector

How do I fix B1140 on a Honda?

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

B1140 The door multiplex control unit lost the driver side power window position signal

Q: What does B1140 mean on a Honda?

B1140. The door multiplex control unit lost the driver side power window position signal. Auto up and auto down may stop working. Applies to Honda and Acura models that use this code.

Category: Body
Severity: Body Warning Light
Applies to: Honda and Acura models that use this code

What does B1140 mean on a Honda?

B1140. The door multiplex control unit lost the driver side power window position signal. Auto up and auto down may stop working. This Honda-enhanced code applies to Honda and Acura models that use this code.

Common causes of B1140

Faulty Power Window Master Switch
Power Window Master Switch harness is open or shorted
Power Window Master Switch circuit poor electrical connection
Faulty Door Multiplex Control Unit
Water intrusion in the door connector

How to fix B1140

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

Sources and review

Last updated 2026-09-26.