U04AD code meaning
Invalid Data Received From Hybrid/EV Battery Interface Control Module M
Network system Generic code U04xx codes Check engine light
What U04AD means
With U04AD the series reaches module M, the thirteenth interface board, which only exists in packs larger than the common twelve-module layout. One example of such a size is GM's Hummer EV: Wikipedia describes its Ultium battery as 24 modules in two layers that can be switched from parallel to series for 800 V fast charging. How GM names the monitoring electronics in that pack is not published, and no maker documents U04AD. The code says the battery controller receives M's frames but rejects their content; corrupted counters, checksums or impossible cell values are typical reasons in this code family. Loss of contact would be U01AC, a software mismatch U0346. Reduced power or charging is the likely consequence.
U04AD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor2 to 10 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U04AD
- Battery system warning
- Fast charging slower or refused
Common causes of U04AD
- PossibleCorrupted frames on the internal link (counter or checksum errors)
- PossibleInterface control module M faulty
- Less likelyMeasurement input on board M reporting impossible values
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 m
What each part of U04AD means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| AD | The exact fault in that area. |
What to do next
- Note U04AD 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 U04AD
What does U04AD mean?
U04AD means "Invalid Data Received From Hybrid/EV Battery Interface Control Module M". With U04AD the series reaches module M, the thirteenth interface board, which only exists in packs larger than the common twelve-module layout. It is a generic code, so it means the same on every make.
Is it safe to drive with U04AD?
Drive gently and only to a workshop. With U04AD the car can go into limp mode (reduced power) to protect itself.
Will U04AD fail an emissions test?
Yes, it can. U04AD 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 U04AD to fix?
Difficulty: workshop only. A typical repair takes 2 to 10 hours of work. This is a job for a workshop.
Will U04AD clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.