U0002 The high-speed CAN bus is still working but with too many errors or a poor signal

High-speed CAN bus performance

U0002 in short

U0002 means the high-speed CAN network is working but with too many errors or a poor signal, so messages between modules get lost. Common causes are wiring or connector faults, one module disturbing the bus, or module software. It can bring limp mode or lost power steering, so get it diagnosed soon.

The high-speed CAN bus carries messages between the engine, transmission, brake, steering and other modules at 500 kbps. U0002 sets when a module sees the bus working poorly, with too many errors or a distorted signal. U0001 is the stronger sign that the bus has stopped working altogether.

Because many modules share the bus, symptoms can look unrelated: limp mode, warning lights, a dead speedometer or lost power steering. Some Stellantis bulletins tie U0002 to a specific module, such as the electric steering gear on the Ram 1500 or the steering column module on newer Charger and Cherokee models.

Network faults are usually in the harness, so wiring and the bus resistance should be checked before modules are replaced.

Most likely causes

  1. Wiring, splice or connector fault on the CAN bus

    Common general cause
    Why it ranks here
    Network failures are usually in the harness: corroded splices, wet connectors or damaged twisted pairs that distort the signal.
    What would change this
    Rises if the bus resistance or idle voltage is wrong, or the fault changes when the harness is moved.

  2. Electric power steering module disturbing the bus (Ram 1500)

    Supported by vehicle data
    Why it ranks here
    Ram bulletins describe the EPS and other CAN C modules going offline with U0001 and U0002 on 2019-2023 Ram 1500, and ask technicians to contact FCA before replacing the steering gear.
    What would change this
    Rises on a Ram 1500 with the steering module offline. Falls if the bus is normal with the EPS unplugged.
    How to test the power steering control module

  3. ABS module dropping off or disturbing the bus

    Supported by vehicle data
    Why it ranks here
    A 2016 Jeep Wrangler ABS module dropped on and off the scan with U0002 and other lost-communication codes, and a Ram 2500 owner reports U0002 with the ESC light flashing that a dealer treated with an ABS reflash.
    What would change this
    Rises if the ABS module drops off the scan tool or stores its own internal fault code.
    How to test the brake system control module (abs module)

  4. Steering column module software (2024-2026 Charger, Cherokee, Wagoneer S)

    Supported by vehicle data
    Why it ranks here
    Dodge and Jeep bulletins update the steering column control module when U0002-00 is stored with B2225-29.
    What would change this
    Rises if your vehicle is covered and the module is not on the latest software.

What to test first

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

  1. Scan every module and note which ones store U0002 and which modules do not answer.

    Low riskTool: scan tool that reads all modules

    • IfOne module missing or storing its own fault

      It meansThat module may be disturbing the bus.

      Go to step 2

    • IfMany modules store U0002 and all answer

      It meansTest the bus wiring.

      Go to step 3

  2. Ask a dealer to check your VIN for bulletins that mention U0002.

    Low risk

  3. With the battery disconnected, measure resistance between pins 6 and 14 of the diagnostic connector.

    Use cautionTool: multimeter

    Warning:Disconnecting the battery can reset settings and needs a radio code on some cars. Keep tools off the battery terminals.

  4. Have a shop scope the bus and unplug modules one at a time to see whether the signal recovers.

    Best left to a shopTool: oscilloscope

    Warning:Unplugging brake and steering modules disables those systems; leave it to a technician.

Symptoms

  • Several warning lights at once (ABS, traction, check engine)
  • Limp mode or stuck in one gear Gets more serious: stop and have it checked.
  • Engine stalls while driving Gets more serious: stop and have it checked.
  • Loss of power steering Gets more serious: stop and have it checked.
  • Speedometer or gauges drop out

How to fix

  1. Have the 12-volt battery tested and check that terminals and grounds are clean and tight.

  2. Write down every code from every module before anything is cleared.

  3. Ask a dealer whether your VIN has a bulletin or software update for U0002.

Parts and cost context

  • electric power steering gear:Ram asks technicians to contact FCA before replacing a Ram 1500 steering gear for U0001/U0002. 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

Ram

  • 2019–2024 · 1500

    Supported by vehicle data

    Ram S2308000042 and 9100194: EPS and other CAN C modules offline with U0001/U0002; contact FCA before replacing the steering gear. Whether they are still current is not verified.

  • S2308000042Status unverified

    EPS and other CAN C modules offline, U0001 and U0002

    2019–20231500 · issued · NHTSA 10242756

    CAN C bus codes with the electric steering and other modules offline; the repair was not read.

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

  • 9100194Status unverified

    Contact FCA before replacing the EPS gear for CAN C codes

    2023–20241500 · issued · NHTSA 10242715

    Before replacing the EPS gear for U0001/U0002, contact FCA.

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

Dodge

  • 2024–2026 · Charger

    Supported by vehicle data

    Dodge 08-163-26: steering column module update for U0002-00 with B2225-29. Whether it is still current is not verified.

  • 2012–2013 · Charger

    Supported by vehicle data

    Owners report U0002 with limp mode, stalling on the highway and loss of power steering.

  • 08-163-26Status unverified

    Steering Column Control Module updates

    2024–2026charger · issued · NHTSA 11031443

    SCCM update; codes include U0002-00 and B2225-29.

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

Jeep

  • 2024–2026 · Cherokee

    Supported by vehicle data

    Jeep 08-164-26: steering column module update for U0002-00 with B2225-29 (also Wagoneer S). Whether it is still current is not verified.

  • 08-164-26Status unverified

    Steering Column Control Module updates

    2024–2026cherokee, wagoneer-s · issued · NHTSA 11031444

    SCCM update; codes include U0002-00 and B2225-29.

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

  • 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

    Same system Supported by vehicle data

    U0001 is a full high-speed CAN failure while U0002 is a performance fault on the same bus; Ram bulletins list both together.

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

    Shares causes Possible — needs testing

    A 2019 Jeep Compass owner reports U0002 stored with U0121 and other codes during ABS and brake warnings.

  • U0103A module lost communication with the electronic gear shift module, the computer behind the shifter

    Shares causes Possible — needs testing

    A 2009 Dodge Charger owner reports U0002 with U0103 and repeated limp mode.

  • U1110Manufacturer code: on Jeep and Dodge, U1110 means a module lost the vehicle speed message it expects over the vehicle network

    Shares causes Possible — needs testing

    U0002 appeared with U1110 and U1120 on a 2019 Jeep Compass with brake warnings.

All Module network (CAN bus) communication codes

U0002 questions

What is the difference between U0001 and U0002?

U0001 means the high-speed CAN bus has failed or gone silent. U0002 means it still works but with too many errors or a poor signal.

Sources and review

  1. U0002: High speed CAN communication bus performance — TAT (Technical Automotive Training) scan data codes
  2. Ram S2308000042: EPS and other CAN C modules offline, U0001 and U0002 (2019-2023 1500) — FCA / NHTSA ,
  3. NHTSA complaint ODI 11089704: 2013 Dodge Charger — NHTSA (owner complaint)
  4. NHTSA complaint ODI 11721623: 2016 Jeep Wrangler — NHTSA (owner complaint)
  5. ASE L1 study guide: Network U-codes — Open Exam Prep
  6. Ram 9100194: contact FCA before replacing EPS gear for CAN C codes (2023-2024 1500) — FCA / NHTSA ,
  7. NHTSA complaint ODI 11603764: 2019 Ram 2500 — NHTSA (owner complaint)
  8. Dodge 08-163-26: Steering Column Control Module updates, U0002-00 (2024-2026 Charger) — FCA / NHTSA ,
  9. Jeep 08-164-26: Steering Column Control Module updates, U0002-00 (2024-2026 Cherokee, Wagoneer S) — FCA / NHTSA ,
  10. NHTSA complaint ODI 11748014: 2019 Jeep Compass — NHTSA (owner complaint)
  11. NHTSA complaint ODI 11511445: 2009 Dodge Charger — NHTSA (owner complaint)
  12. NHTSA complaint ODI 10515526: 2012 Dodge Charger — NHTSA (owner complaint)
Last reviewed
Written by
Saurabh K.
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