C05AC: Brake Blending Separation Valve Stuck Closed
Standardized SAE J2012 code · C05xx codes
Safety-critical system. Faults in airbags, brakes, steering or high-voltage components can put people at risk. Follow the manufacturer's service information and safety procedures, or have the vehicle checked by a qualified workshop.
What does C05AC mean?
Brake blending separation valve stuck closed — regen and hydraulic circuits cannot be isolated.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
- High Valve stuck closed
- Low Carbon or debris buildup preventing free movement
- Low Component wear with age - mechanical play
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of C05AC on the same make and model first.
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