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U043A Invalid Data Received From Suspension Control Module B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Suspension control module B is a second chassis controller, often the one that runs adjustable dampers while module A handles levelling. U043A is logged when its frames reach a receiver but fail integrity checks. GM's 2025 tables give the example of the electronic brake module reading the damper control information: a rolling count equal to the previous one or a protection value that does not add up counts as an error, and 8 errors in a sliding window of 16 set the fault. The check runs only between 9 and 16 V, not during engine start and not within 5 s after a power mode change or reset; it is Type C, so no MIL. Ride control may drop to a fixed default and stability functions may be restricted. U0139 is lost contact, U0421 refers to module A.

Likely causes

Damper module resets or hangs, sending frozen counters
Low supply voltage at the suspension module
Software of suspension and brake modules not matched

Symptoms

  • Service suspension or ride control warning
  • Ride noticeably firmer or softer than usual

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–1,000
Time0.3–2.5 h

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

Parts involved

suspension module b

Related codes

U0139U0421U0434

References: gsi.ext.gm.com, en.wikipedia.org.