U01A3 code meaning
Lost Communication With Hybrid/EV Battery Interface Control Module D
Network system Generic code U01xx codes Check engine light
What U01A3 means
U01A3 marks a lost link to battery interface control module D. Before this generic block existed, GM used proprietary numbers for the same fault: the GM U-code list published for the 2011 Saab 9-4X names U2603 to U2606 as the battery energy control module losing hybrid battery interface modules 1 to 4. GM's 2018 hybrid table still groups these older numbers together with U01A0-U01AC and U179C in one fault bundle, so scan reports from different model years may show either form for the same board. In GM's 2016-2019 plug-in tables D is the fourth of eight boards and is rated Type A. One oddity to keep in mind: invalid data from module D is reported as U02A0, outside the U04A row used by its siblings.
U01A3 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 U01A3
- MIL and hybrid/EV warning (GM Type A)
- Limited power, electric range shortened
- Cell voltages of one pack section shown as unavailable
Common causes of U01A3
- Most likelyChain connection from module C to module D interrupted
- PossibleBattery interface control module D defective
- Less likelyScan tool or software generation reports the board under the older GM number
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 dCommunication bus
What each part of U01A3 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A3 | The exact fault in that area. |
What to do next
- Note U01A3 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 U01A3
What does U01A3 mean?
U01A3 means "Lost Communication With Hybrid/EV Battery Interface Control Module D". U01A3 marks a lost link to battery interface control module D. It is a generic code, so it means the same on every make.
Is it safe to drive with U01A3?
Drive gently and only to a workshop. With U01A3 the car can go into limp mode (reduced power) to protect itself.
Will U01A3 fail an emissions test?
Yes, it can. U01A3 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 U01A3 to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will U01A3 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.