U01AF code meaning
Lost Communication With Hybrid/EV Battery Interface Control Module P
Network system Generic code U01xx codes Check engine light
What U01AF means
U01AF closes the row and stands for battery interface control module P, the sixteenth monitoring board; no manufacturer documents it publicly. Some packs exceed that count: according to Wikipedia the Hummer EV battery consists of 24 Ultium modules, although that platform monitors wirelessly and GM does not publish how it maps modules to codes. The code is easily mixed up with its neighbours. U0111, U0112, U014A and U014C mean that a battery energy control module itself has vanished from the vehicle network, and U019B points to the on-board charger. U01AF, by contrast, describes a sub-board inside the pack that only the battery controller can see, so that controller must itself be awake and reachable to log it.
U01AF at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 10 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U01AF
- Battery warning while the battery controller itself still communicates
- Power limited, charging blocked
Common causes of U01AF
- Most likelyInternal link to module P interrupted
- PossibleBattery interface control module P defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery interface module pCommunication bus
What each part of U01AF means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| AF | The exact fault in that area. |
What to do next
- Note U01AF 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 U01AF
What does U01AF mean?
U01AF means "Lost Communication With Hybrid/EV Battery Interface Control Module P". U01AF closes the row and stands for battery interface control module P, the sixteenth monitoring board; no manufacturer documents it publicly. It is a generic code, so it means the same on every make.
Is it safe to drive with U01AF?
Drive gently and only to a workshop. With U01AF the car can go into limp mode (reduced power) to protect itself.
Will U01AF fail an emissions test?
Yes, it can. U01AF is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U01AF to fix?
Difficulty: workshop only. A typical repair takes 1 to 10 hours of work. This is a job for a workshop.
Will U01AF clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.