U01A2 code meaning
Lost Communication With Hybrid/EV Battery Interface Control Module C
Network system Generic code U01xx codes Check engine light
What U01A2 means
U01A2 is stored when battery interface control module C, the third board of the chain, stays silent. How a controller reaches that verdict is spelled out in GM's 2016 hybrid table: the battery system module first logs U179C for one or more missing boards, then orders all boards into a loopback mode that bypasses the daisy chain. A board that answers in this mode still has power and working logic, so the master can separate a broken link from a dead unit and names only the first board it fails to recover; the code passes again once data returns for 100 ms. Audi bulletin 2081028 for the Q5 e (model years 2022 and 2024) lists U01A200 among the codes for modules A to H behind an electrical system malfunction warning.
U01A2 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U01A2
- Electrical system or hybrid warning in the instrument cluster
- Reduced drive power or no electric driving
- Code returns immediately after clearing
Common causes of U01A2
- Most likelyChain link between module B and module C broken (connector, ribbon, pin)
- PossibleModule C fails the loopback test, board defective
- Less likelyBattery controller software that misreads the chain (update available)
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 cCommunication bus
What each part of U01A2 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A2 | The exact fault in that area. |
What to do next
- Note U01A2 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 U01A2
What does U01A2 mean?
U01A2 means "Lost Communication With Hybrid/EV Battery Interface Control Module C". U01A2 is stored when battery interface control module C, the third board of the chain, stays silent. It is a generic code, so it means the same on every make.
Is it safe to drive with U01A2?
Drive gently and only to a workshop. With U01A2 the car can go into limp mode (reduced power) to protect itself.
Will U01A2 fail an emissions test?
Yes, it can. U01A2 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 U01A2 to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will U01A2 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.