U04AB code meaning
Invalid Data Received From Hybrid/EV Battery Interface Control Module K
Network system Generic code U04xx codes Check engine light
What U04AB means
U04AB means interface module K, the eleventh, delivers data the battery controller judges invalid. What those boards report, cell voltages and temperatures, are exactly the inputs that CARB rule 1968.2, paragraph (e)(15.2.3)(A)(iv), names for monitoring in a hybrid energy storage system; this is why plug-in hybrids light the MIL for such faults, while battery-electric cars, which fall outside these rules, show a battery or system warning instead. With part of the pack unreadable, the controller has to assume the worst for those cells: tighter charge and discharge limits or a blocked charge. No manufacturer documents U04AB publicly, and an eleventh board only exists in larger packs. U01AA covers loss of contact, U0344 a software mismatch.
U04AB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1.5 to 10 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U04AB
- MIL (plug-in hybrid) or battery warning (EV)
- Charging blocked or slowed
- Reduced acceleration
Common causes of U04AB
- PossibleFaulty temperature or voltage input on board K
- PossibleContact fault on the internal data link to module K
- Less likelyInterface control module K internally faulty
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 k
What each part of U04AB means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| AB | The exact fault in that area. |
What to do next
- Note U04AB 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 U04AB
What does U04AB mean?
U04AB means "Invalid Data Received From Hybrid/EV Battery Interface Control Module K". U04AB means interface module K, the eleventh, delivers data the battery controller judges invalid. It is a generic code, so it means the same on every make.
Is it safe to drive with U04AB?
Drive gently and only to a workshop. With U04AB the car can go into limp mode (reduced power) to protect itself.
Will U04AB fail an emissions test?
Yes, it can. U04AB 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 U04AB to fix?
Difficulty: workshop only. A typical repair takes 1.5 to 10 hours of work. This is a job for a workshop.
Will U04AB clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.