Network, generic

U028C Lost Communication With Active Grille Air Shutter Module D

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Module D is the fourth grille shutter address in the code list and only matters on fronts with four independently driven flap units, for instance upper and lower flaps on each side. No manufacturer documents U028C or says where unit D sits, so its position is maker-specific. The surrounding evidence is consistent: Hyundai's 2026 Palisade already splits its lower flaps into left and right actuators and stores U0285 and U028B, with the engine lamp, after water corrodes their plugs (26-01-026H). GM's 2018 engine controller counts a shutter that misses three LIN responses in Run at 11 V or more as a two-trip MIL fault. Under CARB rules, grille shutters belong to the active off-cycle features whose operating time is recorded. A silent unit D leaves its flaps frozen.

Likely causes

Moisture or corrosion at the connector of shutter D
LIN or supply wire to unit D damaged in the front end
Actuator D failed, for example after ice or impact
Wrong actuator variant or configuration after a repair

Symptoms

  • Check engine lamp on
  • Part of the shutters stays open or closed
  • Slightly longer warm-up or higher consumption

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 dvehicle bus wiring

Related codes

U028BU0285U0284U058D

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