C0566Brake Booster Solenoid Circuit/Open
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- Some vacuum brake boosters carry an electrically operated valve that lets air into the working chamber without pedal input – for emergency brake assist or, on hybrids, to blend friction and regenerative braking. An Aisin patent shows the idea: when energised, the solenoid admits atmospheric pressure to an auxiliary chamber and raises boost. C0566 reports an open circuit in this solenoid's wiring or coil. Ford's 2015–2019 hybrids store the ABS fault C0022 (brake booster solenoid) and mirror it as C0566 in the hybrid powertrain module; while it is active, Ford's pump motor and valve tests are suspended. Normal pedal boost usually remains, but automatic brake assist and smooth blending are lost.
- What you may notice
- Brake system or stability warning
- Brake assist or regenerative blending unavailable
- Pedal feel changes on hybrids
- Likely causes
- LikelySolenoid connector loose, unlatched or corroded at the booster
- PossibleBroken wire between ABS module and booster solenoid
- PossibleOpen solenoid coil inside the booster
- Repair
- Medium · Usually a job for a workshop.Typical cost: €40 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.