What causes B1057 on a Honda?

Internal failure in the relay control module Open circuit in the relay control module harness High resistance at the relay module connector Failed multiplex integrated control unit (MICU) Corroded data link pins between the two modules

How do I fix B1057 on a Honda?

Confirm the code with a scan tool and check all related faults Inspect both ends of the data link for corrosion, moisture, and loose pins Test the data link for continuity and short to ground Repair the damaged wiring before swapping any module Replace the relay control module that fails testing Clear the code and retest

B1057 The relay control module lost communication with the multiplex integrated control unit

Q: What does B1057 mean on a Honda?

B1057. The relay control module lost communication with the multiplex integrated control unit. Circuits that rely on that link may stop working. Applies to Honda and Acura models that use this code.

Category: Network Communications
Severity: Check Engine Light
Applies to: Honda and Acura models that use this code

What does B1057 mean on a Honda?

B1057. The relay control module lost communication with the multiplex integrated control unit. Circuits that rely on that link may stop working. This Honda-enhanced code applies to Honda and Acura models that use this code.

Common causes of B1057

Internal failure in the relay control module
Open circuit in the relay control module harness
High resistance at the relay module connector
Failed multiplex integrated control unit (MICU)
Corroded data link pins between the two modules

How to fix B1057

Confirm the code with a scan tool and check all related faults
Inspect both ends of the data link for corrosion, moisture, and loose pins
Test the data link for continuity and short to ground
Repair the damaged wiring before swapping any module
Replace the relay control module that fails testing
Clear the code and retest

Sources and review

Last updated 2026-10-10.