OBD-II code · Chassis
C056F Brake Booster Travel Sensor Circuit Low
Brake booster travel sensor signal voltage below expected range. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.
Is it safe to drive with C056F?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelySignal wire shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
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
- 1–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Brake Booster Travel Sensor
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.