Network, generic

U0543 Invalid Data Received From Headlamp Control Module B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Headlamp control module B is the second light controller, usually serving the headlamp opposite module A. Bentley's 2019-2020 Continental GT campaign (2056293/1) handles the two as light control left and right, at diagnostic addresses 29 and 39, and both needed new software when the outer daytime running lights failed. Jaguar's 2020 XE likewise names HCMA and HCMB (SSM74402). Which side B covers remains vehicle-specific. No public manufacturer text uses U0543; it marks data from B reaching the network in a form the receiver cannot accept. Matrix or bending light then normally falls back to a fixed low beam on the affected side, and a lighting warning appears. Swapping a headlamp without coding or running mismatched software levels left and right are typical triggers. U0242 means B is silent; A is U0542.

Likely causes

Different or outdated software in headlamp module B compared with A
Headlamp B replaced without coding
Internal fault in headlamp module B

Symptoms

  • Lighting system warning in the cluster
  • Matrix or bending light on one side fixed to low beam
  • Daytime running light on one side out

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–900
Time0.3–2.5 h

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

Parts involved

headlamp module b

Related codes

U0242U0542U0241

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