B1556: Ignition Run/Start Circuit Open
MediumBodyBody Electronics
What does B1556 mean?
B1556 is a diagnostic trouble code indicating "Ignition Run/Start Circuit Open". This means there is an electrical break in the body electronics wiring — a connector may be unplugged, a wire broken, or a component has failed internally. The ECU detected no signal where it expected one.
Common causes
- Damaged or corroded wiring harness
- Loose or disconnected electrical connector
- Failed body electronics sensor or actuator
- Blown fuse in the related circuit
- Poor ground connection
What should you do?
Schedule a diagnostic appointment at your earliest convenience. The vehicle is generally safe to drive short distances, but the underlying issue should be addressed to prevent it from worsening.
Get a diagnosis for YOUR car
Code B1556 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.