Network, generic

U0466 Invalid Data Received From HVAC Control Module - Rear

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0466 concerns the rear HVAC control module, the second climate controller in vans, minivans and large SUVs that runs its own blower, blend flaps and often a separate control panel for the back rows. A receiver such as the front climate unit or the body controller sets the code when the rear module's frames carry bad checksums, stalled counters or settings it cannot accept. No manufacturer documents U0466 publicly. For the front unit GM describes the equivalent check in its 2025 body controller: counters, protection values and CRCs of the HVAC messages are tested every 10 ms, and 8 failures within 10 samples set U0424 as Type B. U0165 means the rear module is silent, U0424 covers bad data from the front unit. The rear zone then ignores its controls or holds a fixed setting, while engine and front climate stay normal; no MIL.

Likely causes

Loose or corroded connector at the rear HVAC module, often in the rear trim or headliner
Software mismatch after replacing or programming one of the climate modules
Weak battery or voltage dips at the module
Internal fault in the rear HVAC control module

Symptoms

  • Rear climate controls do not respond
  • Rear blower or temperature stuck at one setting
  • Climate warning or fault message in the display

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–700
Time0.5–3 h

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

Parts involved

rear hvac module

Related codes

U0165U0424U0164U0664

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