What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
B12C5Engine Start/Stop Switch FailureManufacturer communications
2Original wording in English
HONDA
Reported code forms B12C5
Owner Notification Letter - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, the MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch…
HONDA
Reported code forms B12C5
Service Bulletin - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch Failure) is stored.…
Check vehicle applicability
2A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.