U0420 A module received implausible data from the power steering control module

Invalid data received from power steering control module

U0420 in short

U0420 means a module received data from the power steering module that did not make sense. Low battery voltage, steering module software or calibration, and wiring or ground faults are documented causes. Have it checked soon, and stop in a safe place if the steering suddenly gets heavy or a steering warning appears.

The electric power steering module shares steering angle and status data with the ABS, stability, camera and chassis modules. U0420 means it is still sending messages, but one was invalid, often because the steering module flagged a problem of its own.

Several bulletins tie U0420 to voltage: Lincoln says low voltage during a start can set it on the 2019 MKC, Mazda says a voltage dip while cranking stops the steering module from learning its center position, and Land Rover lists low battery voltage and bad steering grounds alongside heavy steering.

The module that stored U0420 tells you what is affected: the ABS module on Lincoln and GM trucks, the front camera on Mazdas, and the chassis module on Land Rovers.

Most likely causes

  1. Low battery voltage, especially while cranking

    Supported by vehicle data
    Why it ranks here
    Lincoln SSM 48083, Mazda 15-003-20 and Land Rover SSM71278 all name low or falling battery voltage as a cause, and a Colorado dealer recharged the battery for U0420.
    What would change this
    Rises if the battery is weak or the code appears right after starting. Falls if the battery tests good.

  2. Steering or brake module software, or a steering sensor that was not calibrated

    Supported by vehicle data
    Why it ranks here
    Lincoln reprograms the ABS module and Mazda updated the steering module software for U0420; a Colorado dealer found a torque sensor not properly learned and did the steering module setup.
    What would change this
    Rises if a dealer finds an update or a calibration code for your VIN. Falls if software is current and setup passes.
    How to test the power steering control module

  3. Wiring, connector corrosion or a poor ground

    Supported by vehicle data
    Why it ranks here
    Land Rover SSM71278 names harness faults and high resistance at the steering grounds, and GM PIT5499 has technicians check the brake module connector for water and corrosion on the 2015-2016 Colorado and Canyon.
    What would change this
    Rises if U0420 comes with lost-communication codes or corrosion is found. Falls if grounds and connectors check clean.

  4. Faulty power steering module or steering gear sensor

    Possible — needs testing
    Why it ranks here
    Dealers replaced the steering gear for U0420 on a 2015 Taurus (angle sensor) and called out a failed steering unit on a 2023 CR-V Hybrid; TaT also names steering module faults. These are single cases that need testing to confirm.
    What would change this
    Rises if the steering module stores its own internal or sensor codes. Falls if voltage, software and wiring fixes clear it.
    How to test the power steering control module

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 module stored U0420 and any steering, ABS or voltage codes.

    Low riskTool: scan tool that reads all modules

    • IfSteering module codes (sensor, voltage or internal) are stored

      It meansHave a shop diagnose the steering system.

      Go to step 4

    • IfU0420 is in the ABS, camera or chassis module with no steering codes

      It meansCheck the battery and software first.

      Go to step 2

  2. Have the battery and charging system tested.

    Low riskTool: battery tester

  3. Ask a dealer whether your VIN has a bulletin, update or steering setup procedure for U0420.

    Low risk

  4. Have a shop check the steering module grounds, connectors and network wiring.

    Best left to a shopTool: multimeter, scan tool

    Warning:This is part of the steering system. Do not probe connectors with the ignition on, and avoid yellow airbag connectors. Let a shop do it if unsure.

Symptoms

  • Stability, traction control or hill start assist warnings
  • ABS light, low brake fluid lamp or Service Trailer Brake message on some GM trucks
  • Front camera or automatic braking warning right after starting (Mazda)
  • Steering suddenly heavy or a steering warning 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

  • Power steering control module:On many cars the steering module is part of the steering column or rack, and some dealers replace the whole assembly. It usually needs setup or calibration afterwards. Labor 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

Chevrolet

  • 2015–2016 · Colorado

    Supported by vehicle data

    GM PIT5499 covers U0420 with brake warnings from a wet or corroded brake module connector (also Canyon). Owner complaints describe loss of power steering, with dealers doing a steering module setup or recharging the battery. Whether it is still current is not verified.

  • PIT5499Status unverified

    ABS/MIL, low brake fluid or Service Trailer Brake with U0420

    2015–2016colorado · issued · NHTSA 10113931

    Inspect the brake module connector for water or corrosion; replace the module and terminals if found. Also covers GMC Canyon.

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

  • 17NA190Status unverified

    Diagnosis information for DTC U0420

    2016–2018malibu · issued · NHTSA 10137405

    Informational bulletin for technicians diagnosing U0420. Also covers Buick LaCrosse.

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

Lincoln

  • 2019 · MKC

    Supported by vehicle data

    Lincoln SSM 48083: U0420 in the ABS module from low voltage during a start; reprogram the ABS module. Whether it is still current is not verified.

  • SSM 48083Status unverified

    Stability messages with U0420 in the ABS module

    2019mkc · issued · NHTSA 10163586

    U0420 and U0415 set by low voltage during a start; reprogram the ABS module.

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

Mazda

  • 2017–2020 · CX-5

    Supported by vehicle data

    Mazda 15-003-20: U0420:68 in the front camera after start, fixed with steering module software (also CX-9, Mazda3, Mazda6). Whether it is still current is not verified.

  • 15-003-20-3737Status unverified

    SBS/SCBS warning with U0420:68 after start

    2017–2020cx-5, cx-9, mazda3, mazda6 · issued · NHTSA 10180670

    Voltage dip while cranking stops steering center learning; steering module software modified.

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

Land Rover

  • 2013–2016 · Range Rover Sport

    Supported by vehicle data

    Land Rover SSM71278: heavy steering with U0420-68 in the chassis module; check battery voltage, harness and steering grounds. Whether it is still current is not verified.

  • SSM71278Status unverified

    Heavy steering with EPAS and CAN DTCs

    2012–2016range-rover-sport, range-rover, range-rover-evoque, discovery-sport · issued · NHTSA 10106046

    Heavy steering with B1304-16, U3001-00, U0001, U0131, U3003-62 and U0420-68; causes include low battery voltage, harness faults and high-resistance steering grounds.

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

  • U0415A module received invalid data from the anti-lock brake (ABS) module

    Same system Supported by vehicle data

    Lincoln SSM 48083 lists U0420 in the ABS module and U0415 in the steering module together, set by low voltage during a start.

  • U0131Lost communication with the power steering control module

    Same system Supported by vehicle data

    Land Rover SSM71278 lists U0131 (lost communication with the steering module) and U0420 together in the chassis module.

  • U3003Manufacturer code: on Ford, Lincoln, Mazda and Honda, the module that stored it saw its battery supply voltage outside the allowed range, usually too low

    Shares causes Supported by vehicle data

    Land Rover SSM71278 lists U3003-62 (battery voltage) with U0420-68; low 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 bus codes with U0420-68.

  • U0121Lost communication with the anti-lock brake (ABS) module

    Shares causes Supported by vehicle data

    GM PIT5499 lists U0121, U0415 and U0420 for water or corrosion at the brake module connector.

All Module network (CAN bus) communication codes

U0420 questions

Can a weak battery cause U0420?

Yes. Lincoln, Mazda and Land Rover bulletins all name low or dipping battery voltage as a cause, so test the battery before replacing steering parts.

Is it safe to drive with U0420?

Have it checked soon. If the steering suddenly becomes heavy or a steering warning says not to drive, stop in a safe place.

Sources and review

  1. TaT fault code library: U0420 Invalid Data Received From Power Steering Control Module — TaT (Technical and Training) Scan Data
  2. Land Rover SSM71278: heavy steering with EPAS and CAN DTCs (2012-2016) — Jaguar Land Rover North America / NHTSA ,
  3. NHTSA complaint 11366940: 2016 Chevrolet Colorado, loss of power steering with U0415/U0420 — NHTSA Office of Defects Investigation
  4. 2023 Integra Owner's Manual: Indicator, Coming On/Blinking — American Honda Motor Co.
  5. Lincoln SSM 48083: stability messages with U0420 in the ABS module (2019 MKC) — Ford Motor Company / NHTSA ,
  6. Mazda 15-003-20: SBS/SCBS warning with U0420:68 after start (2017-2020) — Mazda North American Operations / NHTSA ,
  7. NHTSA complaint 11082248: 2015 Chevrolet Colorado, U0420 torque sensor not learned — NHTSA Office of Defects Investigation
  8. GM PIT5499: ABS/MIL, low brake fluid or Service Trailer Brake with U0420 (2015-2016 Colorado/Canyon) — General Motors / NHTSA ,
  9. ASE L1 study guide: Network U-codes — Open Exam Prep
  10. NHTSA complaint 11265265: 2015 Ford Taurus, heavy steering with U0420 and C200D — NHTSA Office of Defects Investigation
  11. NHTSA complaint 11745935: 2023 Honda CR-V Hybrid, U0420-68 — NHTSA Office of Defects Investigation
  12. GM 17NA190: diagnosis information for DTC U0420 (2016-2018 Malibu, LaCrosse) — General Motors / NHTSA ,
Last reviewed
Written by
Saurabh K.
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