C054D code meaning
Vacuum Sensor B Circuit/Open
What C054D means
Circuit fault on a second vacuum sensor, labelled B, typically an open in its signal, ground or feed. Some systems carry more than one vacuum measurement, for example a booster sensor next to one on the pump or supply line, but which sensor is B is not published by any maker, and no manufacturer documents C054D. The monitoring follows the same pattern as for sensor A: Mitsubishi's brake unit in the 2023 Outlander PHEV recognises an open, a short or a noisy vacuum sensor signal within a second (its own code C1073) and drops brake assist. HELLA's sensor wiring is simple – one pin each for output, ground and supply – so inspection starts at the connector. C0549 is the same fault on sensor A; C054E to C0550 are plausibility, low and high faults of B.
C054D at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.2 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C054D
- Brake system or brake assist warning
- Vacuum pump control in fallback, pump running longer
Common causes of C054D
- Most likelyConnector of sensor B unplugged, loose or corroded
- PossibleInterrupted wire in the sensor harness
- Less likelySensor B open internally
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Vacuum sensor bSensor wiring
What each part of C054D means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4D | The exact fault in that area. |
What to do next
- Note C054D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C054D
What does C054D mean?
C054D means "Vacuum Sensor B Circuit/Open". Circuit fault on a second vacuum sensor, labelled B, typically an open in its signal, ground or feed. It is a generic code, so it means the same on every make.
Is it safe to drive with C054D?
Drive gently and only to a workshop. With C054D the car can go into limp mode (reduced power) to protect itself.
Will C054D fail an emissions test?
C054D is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C054D to fix?
Difficulty: easy. A typical repair takes 0.2 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will C054D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.