U065F code meaning
Lost Communication With Left Rear Temperature Actuator A
What U065F means
Vehicles with a separately controlled rear climate zone need their own temperature doors for the rear outlets, and in a split rear system the left side may use two of them, labelled A and B. Hanon's US 11,305,608 shows why two can be needed: one door ahead of the heater core and a second behind it mixing warm air into the rear cold-air duct. Which door counts as A is up to the maker. GM uses this code: bulletin 23-NA-206 lists U065F-00 in the body control module of the CT4, CT5, Corvette, Escalade, Tahoe, Suburban and Yukon from model year 2020 or 2021 on as a history code from software anomalies that turns on no lamp and may be ignored; if it is current, normal diagnosis applies. A real loss leaves the rear left air at one temperature.
U065F at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.2 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U065F
- Often none when the code is only stored as history
- Rear left air stays hot or cold
- Rear temperature control has no effect on the left
Common causes of U065F
- Most likelySoftware timing between modules logs a false history code (GM)
- PossibleLeft rear temperature actuator A failed
- Less likelyRear HVAC harness or connector damaged in the floor or rear quarter
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Lr temp actuator aVehicle bus wiring
What each part of U065F means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 5F | The exact fault in that area. |
What to do next
- Note U065F and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U065F
What does U065F mean?
U065F means "Lost Communication With Left Rear Temperature Actuator A". Vehicles with a separately controlled rear climate zone need their own temperature doors for the rear outlets, and in a split rear system the left side may use two of them, labelled A and B. It is a generic code, so it means the same on every make.
Is it safe to drive with U065F?
U065F does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U065F fail an emissions test?
U065F is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U065F to fix?
Difficulty: hard. A typical repair takes 0.2 to 4 hours of work. This is a job for a workshop.
Will U065F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.