B2186 The passenger multiplex control unit saw an out of range signal from the front passenger door lock switch

What does B2186 mean on a Honda?

B2186. The passenger multiplex control unit saw an out of range signal from the front passenger door lock switch. The lock and unlock buttons may not respond. This Honda-enhanced code applies to Honda and Acura models that use this code.

Common causes of B2186

• Faulty front passenger door lock switch
• Front passenger door lock switch harness is open or shorted
• Door lock switch circuit poor electrical connection
• Faulty front passenger multiplex control system (MPCS)
• Corroded or loose connector pins at the switch

How to fix B2186

1. Confirm the code with a scan tool and test the door lock and unlock buttons
2. Inspect the switch connector for corrosion, moisture, and loose pins
3. Test the switch signal at the multiplex control unit through lock and unlock
4. Check the wiring for an open or short before replacing the switch
5. Replace the front passenger door lock switch if it fails testing, then clear codes and retest

Sources and review

• Last updated 2026-09-29.