U3003: owner reports and bulletins

Network / communication. We haven't written the explanation for this code yet. Below is what owners and manufacturers have filed with NHTSA.

Got U3003 on your scanner? Tell the mechanic your year, make, model and any symptoms and you'll get the likely cause and what to check first. Ask about this code.

What owners report to NHTSA

24 complaints filed with NHTSA mention U3003, 24 of them since 2015, across 12 different models. The component owners most often filed it under: electrical system.

Most-reported models

VehicleComplaintsModel years reported
HONDA ACCORD52018
MAZDA MAZDA332012, 2018
FORD FUSION32010, 2013, 2014

Manufacturer service bulletins that name U3003

35 technical service bulletins and manufacturer communications filed with NHTSA mention U3003, from 4 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • FORD F-150 (2023, 2024), bulletin 11001367: Some 2023-2024 F-150 non-hybrid/non-Lightning vehicles built on or after 01-Mar-2023 may exhibit an illuminated battery malfunction indicator and/or illuminated ABS malfunction indicator which may be accompanied by a Che…
  • FORD MAVERICK (2022, 2023, 2020, 2021), bulletin 10236028: Some 2020-2023 Escape/Corsair equipped with 2.5L engine full hybrid electric vehicle (FHEV) and plug-in hybrid electric vehicle (PHEV) powertrain and 2022-2023 Maverick vehicles equipped with 2.5L engine FHEV powertrain …
  • LINCOLN CORSAIR PHEV (2021, 2022, 2023), bulletin 10244876: Some 2020-2023 Escape/2021-2023 Corsair equipped with 2.5L engine full hybrid electric vehicle (FHEV) and plug-in hybrid electric vehicle (PHEV) powertrain and 2022-2023 Maverick vehicles equipped with 2.5L engine FHEV p…
  • FORD ESCAPE HYBRID (2020, 2021, 2022, 2023), bulletin 10244876: Some 2020-2023 Escape/2021-2023 Corsair equipped with 2.5L engine full hybrid electric vehicle (FHEV) and plug-in hybrid electric vehicle (PHEV) powertrain and 2022-2023 Maverick vehicles equipped with 2.5L engine FHEV p…
  • FORD F-550 SD (2020, 2021, 2022), bulletin 10206844: Some 2020-2022 F-Super Duty vehicles may exhibit a condition where the engine will not turn off and/or have various electrical symptoms including a dead battery, horn stays on and no crank/no start. The vehicle may also …
  • FORD F-450 SD (2020, 2021, 2022), bulletin 10208141: Some 2020-2022 F-Super Duty vehicles may exhibit a condition where the engine will not turn off and/or have various electrical symptoms including a dead battery, horn stays on and no crank/no start. The vehicle may also …

Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.