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U043E Invalid Data Received From Vacuum Sensor A

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Vacuum sensor A reports the vacuum in a brake booster or vacuum reservoir; U043E is meant for designs in which this sensor sends digital messages and a receiver judges them invalid. No manufacturer documents U043E publicly. GM's usual layout uses an analogue booster vacuum sensor with P-codes: bulletin 17-NA-314 for 2018 Enclave and Traverse traces a Service Power Brake Assist message and brake shudder to wrong readings from a faulty sensor circuit board, setting P0557 and C025E, and 16-NA-366 for 2014-16 Encore links a hard pedal and a constantly running vacuum pump to contamination in sensor, check valve and hose. Comparable effects are plausible with U043E: brake assist warnings, a longer running vacuum pump or start-stop held off. U013D is lost contact; sensor B has U043F.

Likely causes

Faulty sensor electronics giving wrong vacuum values
Oil or dirt in the sensor, check valve or vacuum hose
Poor terminal tension at the sensor connector

Symptoms

  • Brake assist warning message
  • Hard brake pedal or vacuum pump running often

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 a

Related codes

U013DU043FP0556P0557

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