U01AD code meaning
Lost Communication With Hybrid/EV Battery Interface Control Module N
Network system Generic code U01xx codes Check engine light
What U01AD means
U01AD names battery interface control module N, the fourteenth board in a monitoring chain. No manufacturer documents this code publicly, and even GM's broad fault bundle stops at M. The reason such codes exist at all lies in CARB's rule 1968.2, section (e)(15.2.3): hybrid OBD systems must supervise the electronic inputs of the energy storage system, such as cell voltage and temperature sensing, and store separate codes that pinpoint the smallest unit replaceable in service. A pack built from many separately replaceable monitoring boards thus needs one code per board. In a daisy chain of the kind GM describes, a stored U01AD would mean that the boards up to M still answer and N is the first one lost. Neighbouring codes for N are U04AE and U0347.
U01AD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 10 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U01AD
- Battery warning, power and charging limited
- Cell data of one pack section missing in the scan tool
Common causes of U01AD
- Most likelyChain connection between module M and module N interrupted
- PossibleBattery interface control module N defective
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 nCommunication bus
What each part of U01AD 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 U01AD 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 U01AD
What does U01AD mean?
U01AD means "Lost Communication With Hybrid/EV Battery Interface Control Module N". U01AD names battery interface control module N, the fourteenth board in a monitoring chain. It is a generic code, so it means the same on every make.
Is it safe to drive with U01AD?
Drive gently and only to a workshop. With U01AD the car can go into limp mode (reduced power) to protect itself.
Will U01AD fail an emissions test?
Yes, it can. U01AD 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 U01AD to fix?
Difficulty: workshop only. A typical repair takes 1 to 10 hours of work. This is a job for a workshop.
Will U01AD clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.