OBD-II code · Chassis
C0591 Brake Booster Motor A Phase U-V-W Current Low
Brake Booster Motor A Phase U-V-W Current Low: the control module has detected this fault condition. The electric brake booster generates the braking assist; a motor or sensor fault can reduce or disable power-assisted braking. Safety-relevant.
Is it safe to drive with C0591?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyMotor circuit open or load disconnected
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
- 2–6 h
- Emissions test
- Usually unaffected
- Parts involved
- Brake Booster Motor A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.