OBD-II code · Chassis
C0266 Active Brake Booster
The brake control module has detected a fault in the active (electric or vacuum-controlled) brake booster. Active boosters are used by emergency brake assist and adaptive cruise control to autonomously build brake pressure.
Is it safe to drive with C0266?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyActive booster motor or solenoid failed
- PossibleVacuum supply weak (vacuum pump or hose fault)
- Less likelyWiring or connector fault
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Usually unaffected
- Parts involved
- Active Brake Booster, Brake Control Module, Vacuum Pump
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.