U0122 U0122 is a generic network code: a module lost communication with the vehicle dynamics control module, which runs stability control and often shares the ABS hardware

Lost communication with vehicle dynamics control module

U0122 in short

U0122 means another computer lost contact with the vehicle dynamics control module, which handles stability control and often the ABS. Honda and Acura owners report several warning lights with it. Because braking and stability are involved, have a technician diagnose it soon; do not attempt a home repair.

The vehicle dynamics (stability) module shares data with the engine and other computers. If they stop hearing it, they store U0122. The code points to the missing module, not a specific part.

A 2014 CR-V owner reports U0122 with an internal failure in the ABS modulator unit, and an Acura bulletin summary links U0122 to a stability light. A Subaru bulletin summary describes reprogramming how the engine computer detects U0122, so software can matter too.

Because braking and stability are involved, this page explains the code only and gives no repair steps.

Most likely causes

  1. Stability or ABS modulator unit failure

    Supported by vehicle data
    Why it ranks here
    A 2014 CR-V owner was told of an internal failure in the ABS modulator unit, and Honda owners report the code from the dealer readout.
    What would change this
    Rises if the module has its own codes or is silent on the network. Falls if power, ground or wiring faults are found.
    How to test the brake system control module (abs module)

  2. Engine computer software detection

    Supported by vehicle data
    Why it ranks here
    A Subaru bulletin summary for the 2019 Ascent describes engine computer reprogramming that revises how U0122 is detected.
    What would change this
    Rises on the same model years with no module fault. Falls on other makes or with a module that tests bad.
    How to test the engine control module (ecm / pcm)

  3. Network wiring, connector or power problem

    Common general cause
    Why it ranks here
    Lost-communication definitions in TaT cover the module, its power and its network wiring alike.
    What would change this
    Rises with intermittent or multi-module codes. Falls if only one module is silent.

What to test first

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

  1. Read all stored codes from every module and note whether the stability or ABS module has its own codes.

    Low riskTool: scan tool that reads all modules

    • IfThe ABS or stability module has its own codes or does not respond

      It meansA technician should check the module power, ground and network.

      Go to step 2

    • IfOnly U0122 is stored and does not return after clearing

      It meansPossibly a one-off; have it checked if the lights return.

  2. Have a technician test the module power, ground and network signals and check for a service bulletin or software update for the exact car.

    Best left to a shop

    Warning:Brake and stability systems affect stopping ability; leave testing and repair to a trained technician.

Symptoms

  • Stability, VSA, ABS or brake warning lights
  • Red brake light or changed pedal feel Gets more serious: stop and have it checked.
  • Check engine light with U0122

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

  • Brake system control module (ABS module):Honda reports name the ABS modulator unit; replacement should follow a technician confirming the fault; 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

Subaru

  • 11-190-19Status unverified

    ECM reprogramming revises detection of DTC U0122

    2019ascent · issued · NHTSA 10155214

    Reprogram the engine computer to change how U0122 is detected. Only the NHTSA summary was read.

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

Acura

  • 903Status unverified

    VSA light with DTC 25/27 or F-CAN U0122

    2003mdx · issued · NHTSA 10005015

    Describes a VSA indicator with DTC 25 or 27 or F-CAN U0122. Only the NHTSA summary was read.

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

Honda

  • U0129U0129 is a generic network code: a module on the vehicle network lost communication with the brake control module (ABS or stability module), usually stored by the engine, body or instrument computer

    Same system Supported by vehicle data

    U0129 is the matching lost-communication code for the brake control module and was stored with U0122 on a 2024 Accord Hybrid.

All Module network (CAN bus) communication codes

U0122 questions

Is U0122 the same as U0129?

No. U0122 is lost communication with the vehicle dynamics module and U0129 with the brake control module, but on some cars they come from the same hardware and were stored together on a 2024 Accord Hybrid.

Sources and review

  1. NHTSA complaint ODI 11442355: 2018 Honda Accord — NHTSA (owner complaint)
  2. NHTSA complaint ODI 11477246: 2014 Honda CR-V — NHTSA (owner complaint)
  3. Acura 903 (NHTSA 10005015): VSA light with DTC 25/27 or F-CAN U0122 — NHTSA (manufacturer communication)
  4. NHTSA complaint ODI 11589674: 2024 Honda Accord Hybrid — NHTSA (owner complaint)
  5. Subaru 11-190-19 (NHTSA 10155214): ECM reprogramming revises detection of DTC U0122 — NHTSA (manufacturer communication)
  6. U0122 Lost Communication with Vehicle Dynamic Control Module (TaT Scandata) — TaT Scandata fault code library
  7. U0129 Missing Communication with Brake Control Module A (TaT Scandata) — TaT Scandata fault code library
  8. NHTSA complaint ODI 11499832: 2014 Acura RLX — NHTSA (owner complaint)
Last reviewed
Written by
Saurabh K.
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