OBD-II code · Chassis
C0400 Traction Control Solenoid Valve Circuit
The dedicated traction control isolation valve in the hydraulic block reports an electrical fault.
Is it safe to drive with C0400?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelySolenoid coil open
- PossibleShort to ground
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
- 2–5 h
- Emissions test
- Usually unaffected
- Parts involved
- Tcs Isolation Valve, ABS Hydraulic Block, ABS Control Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.