U0663Lost Communication With Rear Mode Actuator
- Generic OBD-II code · Network
- How the car detects it
- The rear mode actuator steers rear-seat air between upper outlets, such as console or roof vents, and the rear footwell. Hanon's US 11,305,608 shows a dome-shaped rear mode door doing exactly this between console vent and rear floor vent. GM uses the code: bulletin 23-NA-206 lists U0663-00, under GM's own name with the suffix Left, in the body control module of Cadillac, Corvette, Tahoe, Suburban and Yukon models from 2020 or 2021 on, as a history entry caused by software that sets no lamp and can be ignored unless it is current. The added word Left suggests GM may split rear distribution by side. When the link is truly lost, rear passengers get air only from the outlets that were open last, for instance warm air at the face or cold air at the feet.
- What you may notice
- No symptom if the code is only stored as history
- Rear air stuck at the console or roof vents or at the floor
- Rear mode button has no effect
- Likely causes
- LikelySoftware timing in the body or climate module storing a false history code (GM)
- PossibleRear mode actuator failed
- RareHarness to the rear HVAC unit or console damaged
- Repair
- Hard · Usually a job for a workshop.Typical cost: €0 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.