U013DLost Communication With Vacuum Sensor A
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- U013D stands for lost communication with vacuum sensor A, a networked sensor that reports the vacuum in the brake booster or a vacuum reservoir. Engines with little manifold vacuum, such as turbocharged direct-injection units, and hybrids use this value to switch on an electric vacuum pump or to throttle the engine so the brake assist stays sufficient. No manufacturer documents U013D in public; GM's 2019 ECM tables show the analog form of this sensor with codes P0556 to P0558, classified as Type B. CARB demands a separate code for lost communication of digital inputs. Sensor B uses U013E, invalid data from sensor A U043E. Possible effects: brake assist warning, start-stop disabled, MIL depending on the manufacturer.
- What you may notice
- Brake booster or brake assist warning
- Electric vacuum pump runs constantly or start-stop disabled
- MIL on depending on the manufacturer
- Likely causes
- LikelyLoose or corroded connector at the vacuum sensor on the booster
- PossibleSupply, ground or bus wiring of the sensor faulty
- RareVacuum sensor A internally faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.