CAN network

U0124 — Lost Communication with Lateral Accelerometer Module

Severity: medium Drive with care, to a shop

What U0124 means

U0124 means one or more control modules stopped receiving messages from the lateral (side-to-side) accelerometer module over the CAN bus. The stability control system (ESC) compares this sensor with yaw rate, steering angle and wheel speeds to detect a skid. Without that data the system can't work properly, so it disables the related functions.

Symptoms

  • ESC/stability control warning light on
  • ABS, traction control or other warning lamps may light up
  • Stability control does not step in during a skid
  • Other chassis and network codes stored along with U0124
  • Some functions of the affected modules unavailable

Possible causes

  1. Failed lateral accelerometer, including one built into the SDM or a suspension module
  2. Open, shorted or chafed CAN bus wiring
  3. Corroded or loose connectors and terminals
  4. Power supply or ground fault at the sensor module
  5. Low system voltage or a weak battery
  6. A faulty module loading down the CAN bus

How to diagnose

  1. Run a full scan of all modules and map which ones are not communicating
  2. Check battery voltage and charging output; charge or replace the battery if needed
  3. Inspect the accelerometer module's connector and harness for corrosion, moisture and chafing
  4. Test the module's power and ground against the wiring diagram
  5. Measure CAN bus resistance (typically about 60 ohms between CAN-H and CAN-L) and voltages at the diagnostic connector
  6. Disconnect suspect modules one at a time, only following a documented procedure, and watch how the bus responds
  7. Clear codes and see if U0124 returns; calibrate the sensor after repair if required

Common fixes

  • Repair open, shorted or chafed CAN wiring
  • Clean or replace corroded connectors and terminals
  • Restore power and ground to the module
  • Replace the faulty accelerometer or module and calibrate it
  • Replace the module that is disrupting the bus and program it if needed

Questions and answers

What does U0124 mean?

It means communication with the lateral accelerometer module was lost. Other modules aren't receiving its data over the CAN bus, so stability control usually shuts off.

Can I drive with a U0124 code?

Usually yes, but carefully, since stability control won't help in a skid. Slow down on wet or slippery roads and get it diagnosed soon.

Why do other codes appear with U0124?

If the cause is the CAN bus, power or ground, several modules lose communication at once. Find the common cause first instead of replacing the sensor by guesswork.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.