C054FVacuum Sensor B Circuit Low
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- The voltage from vacuum sensor B is lower than any value its characteristic allows. Taking HELLA's booster sensor as the reference, the output should never drop below 0.4 V, while 0.5 V corresponds to no vacuum at all; a reading underneath that is electrical rather than physical. A signal line grounded through chafing, a lost 5-V supply or a sensor with a dead output stage are the usual sources, and a low supply (C0548) can contribute. Mitsubishi's brake unit shows that short circuits on the brake vacuum sensor are caught within one second. Bosch lists pump control and stop-start among the functions fed by this measurement, so they fall back when it is lost. No maker documents C054F publicly. C0550 is the high fault, C054B the low fault of sensor A.
- What you may notice
- Brake assist warning shown
- Stop-start unavailable
- Likely causes
- LikelySignal wire of sensor B grounded
- PossibleNo 5-V feed at sensor B
- RareOutput stage of sensor B failed
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.