U3003 Manufacturer code: on Ford, Lincoln, Mazda and Honda, the module that stored it saw its battery supply voltage outside the allowed range, usually too low

Module battery voltage out of range (manufacturer specific)

U3003 in short

On Ford, Lincoln, Mazda and Honda, U3003 means a module saw its battery supply voltage out of range, usually too low. A weak or discharged 12V battery is the most common cause. Because it can disable brake and steering functions, have the battery and charging system tested soon.

U3003 is a manufacturer code, read together with the module that stored it and the suffix after it. On the makes covered here it means that module saw its own supply voltage outside the range it needs. Suffix 16 means too low, and Mazda uses 17 for too high.

Most bulletins blame the 12V battery: low state of charge, a deep discharge or a low-voltage event during a start. Ford's power running boards switch off, Mazda power liftgates stop working, and the 2023 F-150 can show Check Brake System.

Some cases are not the battery. Ford Super Duty trucks can get water in the battery junction box, Ford hybrids can open a high-current fuse, and Honda dealers have found aftermarket splices on module power. Steering and brake modules can lose assist when voltage drops.

Pick your make

U3003 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Weak, discharged or low state-of-charge 12V battery

    Supported by vehicle data
    Why it ranks here
    Ford (SSM 46076, 50154, 52062, 49662) and Mazda (1104M, MT-003-20) bulletins all name low battery voltage or a discharged battery as the cause.
    What would change this
    Rises if the battery fails a load test or the code followed a dead battery or jump start. Falls if the battery tests good and the code returns.

  2. Charging system fault, including the DC/DC converter or its fuse on hybrids

    Supported by vehicle data
    Why it ranks here
    Ford says to inspect the charging system for running-board U3003:16, and traces hybrid U3003:62 to an open 300 A fuse feeding the DC/DC converter.
    What would change this
    Rises if a good battery runs down again or the charging warning comes on.

  3. Water or corrosion in the battery junction box

    Supported by vehicle data
    Why it ranks here
    Ford ties U3003 in the ABS module of 2020-2022 Super Duty trucks to water in the battery junction box from an unseated or broken cover.
    What would change this
    Rises if the junction box cover is loose or broken, or there is moisture or corrosion inside.
    How to test the underhood fuse block (engine compartment fuse box)

  4. Poor power feed to the module, including aftermarket splices

    Supported by vehicle data
    Why it ranks here
    A Honda dealer blamed U3003-16 on an aftermarket quick-splice, and a Mazda dealer blamed EPB U3003 on a dash cam; both are owner-reported dealer findings.
    What would change this
    Rises if an aftermarket device is tapped into the module's wiring or the module's feed drops under load.

  5. Steering module software needs an update

    Supported by vehicle data
    Why it ranks here
    Ford reprograms the power steering module for U3003 on the 2019 Transit Connect and the 2018 F-150 after charging the battery.
    What would change this
    Rises if a bulletin covers your VIN and the code returns with a healthy battery.
    How to test the power steering control module

  6. The module itself has failed

    Possible — needs testing
    Why it ranks here
    A Honda dealer replaced an electric brake booster for U3003-16, but the battery later failed too, so voltage should be ruled out first.
    What would change this
    Rises only if the code returns with a good battery, charging system and supply wiring.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Scan all modules and note which one stored U3003, its suffix (such as 16, 17, 62 or 68) and the other codes with it.

    Low riskTool: scan tool that reads all modules

    • IfU3003 in one or more modules, with or without other U-codes

      It meansStart with the battery.

      Go to step 2

  2. Charge the 12V battery fully, load test it and check the terminals, then clear the codes and recheck.

    Low riskTool: battery tester

  3. Have the charging system checked, including the DC/DC converter and its high-current fuse on hybrids.

    Best left to a shopTool: multimeter or charging system tester

    Warning:Hybrid high-voltage parts can cause serious injury; leave hybrid charging checks to a trained technician.

  4. Have a shop inspect the battery junction box for water and the module's power and ground wiring for splices or damage.

    Best left to a shop

    Warning:Brake and steering module wiring is safety-critical; leave repairs to a technician.

  5. Ask a dealer to check your VIN for module reprogramming bulletins.

    Low risk

Symptoms

  • Power liftgate stops working (Mazda)
  • Power running boards switch off (Ford)
  • 12V battery low message, dead battery or no start
  • Electric parking brake or brake system warning (Honda, Mazda) Gets more serious: stop and have it checked.
  • Check Brake System message or ABS light (Ford) Gets more serious: stop and have it checked.
  • Heavy steering or Power Steering Fault message (Ford) Gets more serious: stop and have it checked.

How to fix

This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.

Parts and cost context

  • 12V battery:Test the battery before replacing any module; most bulletins trace U3003 to battery state of charge. Labour varies; get a quote.
  • power steering module:Ford often fixes steering-related U3003 with a battery charge and reprogramming rather than a new module. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Ford

  • 2015–2023 · F-150

    Supported by vehicle data

    U3003 shows in the running board module (SSM 50154), steering module after auto start-stop (SSM 49662) and ABS module on 2023 trucks (SSM 52062), all tied to low battery charge. Whether they are still current is not verified.

  • 2020–2022 · F-250 Super Duty

    Supported by vehicle data

    Ford TSB 22-2044: water in the battery junction box with C0020 and U3003 in ABS. Whether it is still current is not verified.

  • 2019 · Transit Connect

    Supported by vehicle data

    Ford SSM 47792: lack of steering assist with U3003; charge the battery and reprogram or replace the steering module. Whether it is still current is not verified.

  • SSM 46076Status unverified

    P0137 and U3003 from low battery voltage

    2016–2017fusion, c-max · issued · NHTSA 10109069

    Test the battery, repair low voltage and clear codes. Also covers Lincoln MKZ.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • SSM 50154Status unverified

    Power running boards disabled with U3003:16

    2015–2020f-150, expedition, f-250-super-duty · issued · NHTSA 10201606

    Inspect the charging system and correct the low-voltage event, then reset the boards to Auto. Also covers Lincoln Navigator.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • SSM 52062Status unverified

    Check Brake System with U3003:16 in ABS

    2023f-150 · issued · NHTSA 10245259

    Caused by low battery state of charge.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • SSM 52201Status unverified

    12V battery low with U3003:62 in the DC/DC converter

    2020–2023escape, maverick · issued · NHTSA 10249424

    Caused by an open 300 A high-current fuse. Also covers Lincoln Corsair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • SSM 47792Status unverified

    Lack of steering assist with U3003 and U2011

    2019transit-connect · issued · NHTSA 10155564

    Charge the battery, then reprogram or replace the steering module.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • SSM 49662Status unverified

    Heavy steering with U3003:68 after auto start-stop

    2018f-150 · issued · NHTSA 10189562

    Check battery health and reprogram the steering module.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • TSB 22-2044Status unverified

    Water in the battery junction box with C0020 and U3003

    2020–2022f-250-super-duty, f-350-super-duty, f-450-super-duty, f-550-super-duty · issued · NHTSA 10208141

    Inspect and repair the battery junction box and its cover.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Mazda

  • 2016–2021 · CX-9

    Supported by vehicle data

    Mazda 1104M and MT-003-20: power liftgate inoperative with U3003:16 or :17 from battery voltage (also CX-5). Whether they are still current is not verified.

  • MT-003-20Status unverified

    Power liftgate inoperative with U3003:16 or :17

    2016–2021cx-5, cx-9 · issued · NHTSA 10179154

    Caused by low or high battery voltage.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 1104MStatus unverified

    Power liftgate inoperative with U3003:16

    2016cx-9 · issued · NHTSA 10092344

    May be caused by low battery voltage.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Honda

  • 2019 · CR-V

    Supported by vehicle data

    An owner reports the dealer found U3003-16 in the brake booster with brake and parking brake warnings; the battery later failed too.

  • U3000Manufacturer code: on Ford, Honda, Acura and Mazda, the module that stored it found a fault inside itself

    Shares causes Supported by vehicle data

    Ford SSM 52201 lists U3003:62 with U3000:04 on hybrids with an open DC/DC converter fuse.

  • U0420A module received implausible data from the power steering control module

    Shares causes Supported by vehicle data

    Land Rover SSM71278 lists U3003-62 with U0420-68 in the chassis module; low battery voltage is a named cause.

  • U0001A module reports a fault on the high-speed CAN bus itself, the main data network that links the engine, transmission, brake and steering computers

    Shares causes Supported by vehicle data

    Land Rover SSM71278 lists U0001-87/88 high-speed CAN codes alongside U3003-62.

  • U0100Lost communication with the engine or powertrain computer

    Shares causes Supported by vehicle data

    Ford's DPS6 bulletin lists U3003 with U0100 and U0101 on Fiesta and Focus no-start or loss-of-power cases.

All Module network (CAN bus) communication codes

U3003 questions

Does U3003 mean a module is bad?

Usually not. Ford and Mazda bulletins trace it to low battery voltage or a discharged battery; test and charge the battery first.

Can an aftermarket device cause U3003?

It can. Owners report a Honda dealer blaming U3003-16 on an aftermarket wiring splice and a Mazda dealer blaming a dash cam.

Sources and review

  1. Ford SSM 52062: Check Brake System message with U3003:16 in the ABS module (2023 F-150) — Ford Motor Company / NHTSA ,
  2. Ford SSM 49662: heavy steering with U3003:68 after auto start-stop (2018 F-150) — Ford Motor Company / NHTSA ,
  3. Ford SSM 47792: lack of power steering assist with U3003 and U2011 (2019 Transit Connect) — Ford Motor Company / NHTSA ,
  4. NHTSA complaint 11766302: 2019 Honda CR-V brake warnings with U3003-16 — NHTSA Office of Defects Investigation
  5. 2023 Integra Owner's Manual: Indicator, Coming On/Blinking — American Honda Motor Co.
  6. Ford SSM 46076: MIL with P0137 and U3003 in the BECM from low battery voltage (2016-2017 hybrids) — Ford Motor Company / NHTSA ,
  7. Ford SSM 50154: power running boards disabled with U3003:16 in the running board module — Ford Motor Company / NHTSA ,
  8. Mazda 1104M: power liftgate inoperative with U3003:16 (2016 CX-9) — Mazda North American Operations / NHTSA ,
  9. Mazda MT-003-20: power liftgate inoperative with U3003:16 or U3003:17 (2016-2021 CX-5, CX-9) — Mazda North American Operations / NHTSA ,
  10. Ford SSM 52201: 12V battery low with U3003:62 in the DC/DC converter (2.5L hybrids) — Ford Motor Company / NHTSA ,
  11. Ford TSB 22-2044: water in the battery junction box, ABS lamp with C0020 and U3003 (2020-2022 Super Duty) — Ford Motor Company / NHTSA ,
  12. NHTSA complaint 11685172: 2020 Honda Accord Hybrid U3003-16 from an aftermarket splice — NHTSA Office of Defects Investigation
  13. NHTSA complaint 11582867: 2018 Mazda3 EPB U3003 failure type 16 — NHTSA Office of Defects Investigation
  14. Land Rover SSM71278: heavy steering with EPAS and CAN DTCs (2012-2016) — Jaguar Land Rover North America / NHTSA ,
  15. Ford TSB 16-0044: DPS6 no start or loss of power with U0100, U0101, U1013, U3003 and/or P0606 — Ford Motor Company / NHTSA ,
  16. Mazda MT-006-18: power liftgate inoperative with U3003:16 (2016-2018 CX-5, CX-9) — Mazda North American Operations / NHTSA ,
  17. NHTSA complaint 11442336: 2018 Honda Accord electric brake booster U3003-16 — NHTSA Office of Defects Investigation
  18. NHTSA complaint 11710373: 2020 Lincoln Nautilus U3003-16 Battery Voltage Below Threshold — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
Editorial review
Pending
Technician review
Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

My Car

Pick your car and code pages will point out notes and bulletins for it. Saved only in this browser.

Fill this in from your VIN

Used once to identify your engine; not stored.