U0349 code meaning
Software Incompatibility With Hybrid/EV Battery Interface Control Module P
What U0349 means
P is the sixteenth and final letter; the following number, U034A, already names an engine disconnect clutch, so a pack with more than sixteen boards would need maker codes. No vehicle is publicly linked to U0349. A real case of out-of-date battery firmware comes from Rivian: in 2022 R1T trucks built from October 2021 to June 2022, an old BMS firmware version could block over-the-air updates, so campaign RCA-30-23-001 had technicians remove an underbody panel, read a serial label and escalate for a manual update. A version gap can thus stop the update path itself, which is why a mismatch needs the maker's flashing tool. CARB's hybrid rules cover cell sensing; battery-only vehicles fall outside OBD II. U01AF and U04B0 are P's partners.
U0349 at a glance
- Check engine lightUsually not
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.3 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0349
- Software updates fail or are not offered
- Battery warning after battery service
- Charging or power limited in severe cases
Common causes of U0349
- Most likelyBattery firmware so old that over-the-air updates cannot be applied
- PossibleSixteenth board replaced without matching software
- Less likelyCode confused with U034A, which belongs to another component
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 p
What each part of U0349 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 49 | The exact fault in that area. |
What to do next
- Note U0349 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 U0349
What does U0349 mean?
U0349 means "Software Incompatibility With Hybrid/EV Battery Interface Control Module P". P is the sixteenth and final letter; the following number, U034A, already names an engine disconnect clutch, so a pack with more than sixteen boards would need maker codes. It is a generic code, so it means the same on every make.
Is it safe to drive with U0349?
Drive gently and only to a workshop. With U0349 the car can go into limp mode (reduced power) to protect itself.
Will U0349 fail an emissions test?
Yes, it can. U0349 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 U0349 to fix?
Difficulty: workshop only. A typical repair takes 0.3 to 3 hours of work. This is a job for a workshop.
Will U0349 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.