U01A0 code meaning
Lost Communication With Hybrid/EV Battery Interface Control Module A
Network system Generic code U01xx codes Check engine light
What U01A0 means
U01A0 names battery interface control module A, the first slave board that reports cell voltages and temperatures of its pack section to the battery controller. GM's 2016-2019 plug-in hybrid tables explain how the code arises: the battery system module talks to eight such boards over a UART daisy chain; once U179C shows that data has stopped, it switches the boards into an internal loopback test and stores the code of the first board it still cannot reach, in 2016 after 5 s above 10.2 V, Type A with MIL on the first trip. Because A sits next to the master, a break ahead of A silences every board in the chain while only A gets named. Audi lists U01A000 for the 2016 A3 Sportback e-tron, which then refuses to make the drive system ready.
U01A0 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 U01A0
- Vehicle does not become ready to drive, red hybrid/EV warning
- MIL on after the first failing trip (GM Type A)
- Further module codes or U179C stored at the same time
Common causes of U01A0
- Most likelyChain wiring or connector between battery controller and module A interrupted
- PossibleModule A without supply from its cell group or low-voltage feed
- PossibleBattery interface control module A defective
- Less likelyChain interface of the battery controller itself 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 aCommunication bus
What each part of U01A0 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A0 | The exact fault in that area. |
What to do next
- Note U01A0 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 U01A0
What does U01A0 mean?
U01A0 means "Lost Communication With Hybrid/EV Battery Interface Control Module A". U01A0 names battery interface control module A, the first slave board that reports cell voltages and temperatures of its pack section to the battery controller. It is a generic code, so it means the same on every make.
Is it safe to drive with U01A0?
Drive gently and only to a workshop. With U01A0 the car can go into limp mode (reduced power) to protect itself.
Will U01A0 fail an emissions test?
Yes, it can. U01A0 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 U01A0 to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will U01A0 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.