U0346 code meaning
Software Incompatibility With Hybrid/EV Battery Interface Control Module M
What U0346 means
With M the row passes the common twelve-board size. GM's 2018 hybrid table 18OBDG02 includes lost-contact codes for interface modules up to M (U01AC) in its bundle BICM Loss of Comm and adds that GM shares software across programs, so a code counts only where the program in question uses it. A matching bundle for software codes such as U0346 is not listed. The one GM pack plainly beyond twelve modules is the Hummer EV, whose Ultium battery Wikipedia describes as two layers of twelve modules each, wired in parallel at 400 V. How GM addresses the monitoring units in that pack is not published, so no vehicle is known to set U0346. U04AD is M's invalid-data code.
U0346 at a glance
- Check engine lightUsually not
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0346
- Battery or propulsion warning
- Power or charging limited
- Code seen only on very large packs
Common causes of U0346
- Most likelyThirteenth board on a software level the controller rejects
- PossibleController software variant for another pack configuration
- Less likelyBoard installed in the wrong layer or position of a multi-layer pack
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 m
What each part of U0346 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 46 | The exact fault in that area. |
What to do next
- Note U0346 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 U0346
What does U0346 mean?
U0346 means "Software Incompatibility With Hybrid/EV Battery Interface Control Module M". With M the row passes the common twelve-board size. It is a generic code, so it means the same on every make.
Is it safe to drive with U0346?
Drive gently and only to a workshop. With U0346 the car can go into limp mode (reduced power) to protect itself.
Will U0346 fail an emissions test?
Yes, it can. U0346 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 U0346 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U0346 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.