U0122

Lost Communication With Vehicle Dynamics Control Module

Car Fault Codes Network

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 6 hours

Typical cost SAR 100 to 8,000

What it means

A module on the network is no longer receiving messages from the vehicle dynamics control module, the unit that runs stability and traction control (called ESP or VSC depending on the maker). On many vehicles this function lives inside the ABS module itself; on others it is a separate unit. For the driver, stability control usually stops working and its warning lights come on.

Symptoms5

Stability or traction control light on, sometimes with the ABS light.
Stability control does not intervene when the car slides in turns or on slippery roads.
Traction control not working when pulling away on sand or wet roads.
Cluster message asking to service the stability system.
Some driver assist features, such as adaptive cruise, disabled on some vehicles.

Possible causes6

Blown power fuse for the module, or for the ABS module if the function is built into it.
Weak battery or low voltage while running.
Corrosion or water in the module connector.
Poor module ground connection.
Open or shorted CAN wiring to the module.
Internal module failure.

How to diagnose5

Check the service information to see whether stability control is built into the ABS module or is a separate unit, since this changes where to test.
Read codes from all modules and see whether U0121 or other lost-communication codes are also present.
Try to connect directly to the module; if it does not respond, check its fuses, power and ground.
Inspect the module connector for water, corrosion or loose pins.
Measure CAN line resistance and voltages and compare them with the manufacturer specification.

How to fix6

Replace the blown fuse, and charge or replace a weak battery.
Clean the module connector and repair the ground point.
Repair damaged CAN wiring.
Update the module software if the manufacturer has a fix for this issue.
Replace and program the module, or the combined ABS unit, then calibrate the steering angle sensor if required.
Clear codes in all modules, road test and confirm the stability light stays off.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost stays low for a fuse, connector or battery, and rises sharply when the module is built into the ABS hydraulic unit and must be replaced and programmed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

How is this different from U0121?

U0121 is for the ABS module, while this code is for the vehicle dynamics module that runs stability control. On many cars both functions share one unit, so the two codes appear together with one root cause.

Is it safe to drive without stability control?

You can drive carefully, but the car will not correct a slide by itself. Slow down in turns and on wet or sandy roads, and repair it soon.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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