U04C0 code meaning
Invalid Data Received From Battery Management Control Module
What U04C0 means
The battery management control module behind U04C0 is not always the main controller of the high-voltage battery. Mazda uses the code on the CX-90 (2024–2026) and CX-70 (2025–2026) plug-in hybrids for their backup power unit: the PCM stores U04C0:00, which Mazda describes as an internal malfunction there, often together with P143B, U3008 or U3003 and a lit hybrid system warning. Bulletin SA-030-26 traces this to the small AGM sub battery under the passenger floor and has it replaced. GM's 2024 table 24OBDG07 has only the lost-contact sibling U01BF, set by the gateway after 6.5 s without messages from a module called LIBI, Type B, and no U04C0 entry. Not the same as U0412, the invalid-data code of the battery energy control module.
U04C0 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U04C0
- Hybrid system warning light on
- Further codes for the backup power supply stored
Common causes of U04C0
- Most likelyWeak backup sub battery (Mazda CX-90/CX-70 PHEV, AGM YTZ7S)
- PossibleBattery management or backup power unit internally faulty
- Less likelyBus wiring or connector fault to the module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bms
What each part of U04C0 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C0 | The exact fault in that area. |
What to do next
- Note U04C0 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 U04C0
What does U04C0 mean?
U04C0 means "Invalid Data Received From Battery Management Control Module". The battery management control module behind U04C0 is not always the main controller of the high-voltage battery. It is a generic code, so it means the same on every make.
Is it safe to drive with U04C0?
U04C0 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U04C0 fail an emissions test?
U04C0 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U04C0 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will U04C0 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.