AI DamageU3003 code: Battery Voltage
Code U3003 is named in 26 US owner complaints, 2 of them (8%) after a crash. Models: 13, model years 2010–2025.
What the code means
Battery Voltage. Generic meaning per SAE J2012 (the same for all makes).
How to read U3003: the letter U means network communication between modules; the second digit 3 marks a generic SAE code shared by all makes; the last three characters 003 identify the specific fault.
Lost communication codes (U0xxx) mean one module cannot hear another on the data bus. The cause can be the module itself, its power or ground, or a damaged wiring harness. After a crash this is a typical trace: the impact tears wiring in the rail, fender or rocker and modules drop off the network.
Key figures
- Complaints with this code
- 26
- after a crash
- 2 (8%)
- Models
- 13
- Model years
- 2010–2025
Which models and years
Models whose owners name this code (13). Years link to the model year problems page.
| Model | Years | Complaints |
|---|---|---|
| Honda Accord | 2018 | 5 |
| Ford Fusion | 2010, 2013, 2014 | 3 |
| Honda CR-V | 2018, 2019 | 3 |
| Mazda Mazda3 | 2012, 2018 | 3 |
| Ford Explorer | 2013, 2015 | 2 |
| Ford Fiesta | 2013, 2016 | 2 |
| Ford Focus | 2014 | 2 |
| Ford Escape | 2014 | 1 |
| Ford Ranger | 2019 | 1 |
| GMC Sierra 1500 | 2025 | 1 |
| Honda Accord Hybrid | 2020 | 1 |
| Lincoln Nautilus | 2020 | 1 |
| Mazda CX-5 | 2021 | 1 |
Components named together with the code
Component as the owner filed it (one complaint can list several).
Complaints by model year
What to do if an auction car has this code
- Check wiring harnesses in the impact zone: rail, fender, rocker, pillar.
- Check the battery and grounds: low voltage triggers false lost communication codes.
- Budget a network scan: a missing module may be intact while its wiring is damaged.
What owners report
Excerpts of owner complaints in the original wording. Owner statements not verified by the regulator; personal data removed.
On 9/16/26 at 52,113 miles, East Coast Honda finally documented that the electric parking brake warning was going on/off while driving along with the brake-system and battery lights. They found DTC U3003-16, Brake Booster Control Unit Power Circuit Low Voltage, and replaced the electric brake booster.
Estimate for damage to wooden fence $2560, neighbor's garage $8000. Engine code scan report on Oct 10, 2025 engine code U3003-16 Battery Voltage Below Threshold. EEC test at dealer on Oct 14, 2025: "no codes in any systems..." Vehicle damage noted.
On September 4, 2025, my dealership identified a non-genuine purple quick-splice connector in the driverâs door harness, which they attribute to error codes B1142 (Driverâs Door Lock Knob Switch Circuit), U0199 (Lost Communication with Driverâs Door Module), and U3003-16 (Electric Servo Brake Control Unit Power…
Related codes
- U3000Control Module
- U0073Control Module Communication Bus A Off
- U0140Lost Communication With Body Control Module
- U0001High Speed CAN Communication Bus
- U0422Invalid Data Received From Body Control Module
- U0002High Speed CAN Communication Bus Performance
- U0146Lost Communication With Serial Data Gateway…
- U0141Lost Communication With Body Control Module A
- U3006Control Module Input Power A Circuit/Open
- U0010Medium Speed CAN Communication Bus
- U0029Vehicle Communication Bus A Performance
- U3001Control Module Improper Shutdown Performance
Sources: public official US data (owner complaints) and the SAE J2012 standard. Complaints are owner statements not verified by the regulator. A code from a complaint does not replace a scan tool diagnosis. Data updated 2026-11-10.