B1252 The combination switch control unit reported an internal fault

What does B1252 mean on a Honda?

B1252. The combination switch control unit reported an internal fault. Turn signal, wiper, and lighting inputs that share the switch may act up. This Honda-enhanced code applies to Honda and Acura models that use this code.

Common causes of B1252

• Faulty combination switch control unit
• Combination switch control unit harness is open or shorted
• Combination switch control unit circuit poor electrical connection
• Water intrusion or corrosion inside the unit
• Loose or corroded ground at the unit

How to fix B1252

1. Confirm the code with a scan tool and check the MICU for related faults
2. Inspect the combination switch connectors and grounds for corrosion and looseness
3. Test battery voltage and charging to rule out low voltage
4. Check around the unit for water intrusion
5. Replace the combination switch control unit only after tests prove it failed

Sources and review

• Last updated 2026-09-29.