U0122

Universal

Lost Communication With Vehicle Dynamics Control Module

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

The vehicle’s control modules communicate over an electronic network. This code means a module detected that it could not communicate with the Vehicle Dynamics Control Module. Depending on the vehicle, that module may support functions such as stability or traction control. Those functions may be limited or unavailable while communication is lost; the code does not by itself prove that the module has failed.

Report an error with this code

⚠️ Before You Begin (Safety First)

Stability, traction, or related braking assistance may be unavailable. If brake behavior changes, a brake warning appears, or the vehicle feels unstable, pull over somewhere safe and arrange professional help. If the vehicle brakes and handles normally, drive cautiously and have the fault checked promptly; do not rely on stability or traction assistance.

Common Symptoms

  • A stability-control, traction-control, or related warning light may appear if the vehicle can no longer exchange information with the Vehicle Dynamics Control Module.
  • Stability or traction assistance may be reduced or disabled, depending on which functions rely on that module.
  • Other warning lights or messages may appear if related modules also lose information they need.
  • There may be no noticeable symptoms if the communication loss was brief or the code is stored from an earlier event.

Common Causes

  • A temporary network interruption, possibly associated with low or unstable vehicle voltage.
  • A loose, damaged, corroded, or contaminated connector or wire affecting module power, ground, or network communication.
  • A fuse or other power-supply problem affecting the Vehicle Dynamics Control Module.
  • A fault in the vehicle communication network or another connected module disrupting messages.
  • An internal Vehicle Dynamics Control Module fault, which should be considered only after its power, ground, connections, and network have been checked.

Diagnostic Steps

  1. Note which warning lights or messages are present and whether they appeared after a battery problem, repair, or jump-start; this context can help distinguish a temporary voltage event from an ongoing fault.
  2. With the vehicle parked safely and switched off, visually check accessible battery terminals and wiring for looseness or obvious damage. Do not disconnect the battery just to clear the code.
  3. Use the owner’s manual to identify any relevant fuses and inspect them only if the manual provides a safe owner procedure. Replace a fuse only with the specified type and rating; if it blows again, stop and seek diagnosis.
  4. Visually inspect accessible wiring and connectors around the relevant system for obvious damage, moisture, or looseness. Avoid disturbing safety-system wiring or probing connectors.
  5. Arrange a scan of all vehicle modules if the code returns, warning lights remain on, or stability or braking assistance seems affected. Module-network diagnosis may require vehicle-specific service information and electrical test equipment.

When to Call a Professional

Scan all modules for communication and voltage-related codes before clearing anything. Check the Vehicle Dynamics Control Module’s power, ground, connectors, and network wiring, then assess network communication using service information for the specific vehicle. Consider module replacement only after its circuits and network connections have been tested.

Compare component listings

Confirm diagnosis and vehicle fitment before buying. A listing does not prove that a part needs replacement. We may earn a commission from qualifying purchases.

Search Amazon Search eBay

Commonly Asked Questions

Does U0122 prove that the Vehicle Dynamics Control Module is faulty?

No. It indicates a loss of communication, which can result from a power, ground, wiring, connector, network, voltage, or module problem. The communication path should be tested before replacing a module.

Can I drive with U0122?

The answer depends on the symptoms and which functions are affected. If braking behavior changes, the vehicle feels unstable, or a brake warning appears, stop safely and arrange professional help. Otherwise, drive cautiously and have the fault checked promptly.

Why might the code appear even if the vehicle feels normal?

The loss of communication may have been brief or may affect assistance functions that are not noticeable during ordinary driving. A stored code can also remain after the original interruption has passed.

What should be checked before replacing the module?

A technician should scan related modules and check the module’s power, ground, connectors, wiring, and network communication using procedures for the specific vehicle.

Browse Available Code Guides

Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.