U04AF code meaning
Invalid Data Received From Hybrid/EV Battery Interface Control Module O
Network system Generic code U04xx codes Check engine light
What U04AF means
U04AF concerns interface module O, the fifteenth board. In practice a data fault of this kind often follows work on the pack: if a replaced board and the battery controller interpret messages differently, frames arrive formally intact but fail range or counter checks. The software sibling U0348 and a search for available updates therefore belong next to this code, as does U01AE for a module that stopped sending. GM's 2015 note PIC6080 for the 2011–2014 Volt, ELR and Ampera says to reprogram the battery and hybrid controllers first when cell codes are spread over several pack sections, and to call technical assistance only when all of them sit on one interface board. No maker documents U04AF; the letter O only exists on very large packs.
U04AF 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 U04AF
- Battery warning shortly after a battery repair
- Reduced power or charging
Common causes of U04AF
- Most likelySoftware levels of replaced board and battery controller do not match
- PossibleInterface control module O faulty
- Less likelyPlug not fully seated after pack repair
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 o
What each part of U04AF 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 U04AF 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 U04AF
What does U04AF mean?
U04AF means "Invalid Data Received From Hybrid/EV Battery Interface Control Module O". U04AF concerns interface module O, the fifteenth board. It is a generic code, so it means the same on every make.
Is it safe to drive with U04AF?
Drive gently and only to a workshop. With U04AF the car can go into limp mode (reduced power) to protect itself.
Will U04AF fail an emissions test?
Yes, it can. U04AF 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 U04AF to fix?
Difficulty: workshop only. A typical repair takes 1 to 10 hours of work. This is a job for a workshop.
Will U04AF clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.