Network, generic

U043F Invalid Data Received From Vacuum Sensor B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U043F is the counterpart for vacuum sensor B, used where a second vacuum signal exists, for example a redundant booster sensor or one watching a separate reservoir. A receiver records it when B's digital vacuum value arrives invalid. Comparing with U043E narrows the search: B alone points at that sensor or its wiring branch, both together at a shared supply, the bus or a genuine vacuum shortage. No manufacturer documents U043F publicly and no thresholds are known; in GM's analogue designs a booster sensor fault shows up as a P-code such as P0557 instead. Without a trustworthy second value the receiver loses its cross-check between the two sensors, so a brake assist warning and disabled vacuum-dependent functions are the likely consequence. U013E is lost contact.

Likely causes

Faulty vacuum sensor B or its electronics
Damaged wiring branch or connector to sensor B
Actual vacuum leak making both sensors disagree

Symptoms

  • Brake assist or vacuum system warning
  • Start-stop or other vacuum-dependent functions inactive

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–400
Time0.3–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

vacuum sensor b

Related codes

U013EU043EP0557

References: static.nhtsa.gov, en.wikipedia.org.