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U028B Lost Communication With Active Grille Air Shutter Module C

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Shutter module C is a third, separately addressed flap actuator behind the grille or bumper, used where a front end divides its cooling air openings into several sections. Hyundai documents the code: its 2026 Palisade and Palisade Hybrid have left and right actuators for the lower active air flaps, and campaign 26-01-026H lists U028B together with U0285 and flap position codes when water enters the bumper connectors and corrodes them. Owners then see an air flap warning, the check engine lamp and sometimes a low oil message; the remedy is to inspect pins and replace harness, actuators or sensors. How the engine controller decides on lost contact is visible at GM, which sets the code for shutters on the LIN bus after three missed responses as a two-trip fault.

Likely causes

Water ingress and corrosion at the bumper connector of shutter C
Front harness damaged by impact, stone chips or poor routing
Actuator C failed or seized
Fault in the controlling engine module or its LIN output

Symptoms

  • Check engine lamp on
  • Active air flap warning in the cluster
  • Lower flaps no longer move

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.3–3 h

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

Parts involved

active grille shutter module cvehicle bus wiring

Related codes

U028CU0285U0284U058C

References: static.nhtsa.gov, static.nhtsa.gov, gsi.ext.gm.com, law.cornell.edu.