U0122 - DATA BUS: VEHICLE DYNAMICS CONTROL MODULE - NO CONNECTION

Description of DTC code U0122

The controllers installed in the car use a communication protocol called Control Area Network (CAN), through which operating data, commands, and other information are shared. In addition to this, it is through the CAN bus that vehicle information can be obtained using a scan tool.

The exchange of information between the modules is necessary for the correct performance of the car. Among these, we can mention the data sent by the Vehicle Dynamics Control Module (VDC), which is used to avoid wheel locking in an ABS stop, loss of traction when accelerating, and loss of control in a turn or on wet pavements.

The U0122 OBDII fault code indicates that the Vehicle Dynamics Control Module is experiencing problems in the communication it is expected to establish with the corresponding module to the point of complete loss of communication.

How does the U0122 Generic Code work?

This is a generic communication system diagnostic trouble code that usually appears in several brands and models of vehicles. As we already established, this code indicates that the VDC module and probably other vehicle control modules are not connecting correctly. Without this CAN bus, the control modules are unable to communicate and their scan tool might not be able to get information from the vehicle, depending on the present circuitry.

The VDC module is accountable for keeping the tires from sticking when the ABS stops or losing traction when accelerating, not to mention keeping the vehicle from losing control when cornering on wet asphalt or during aggressive driving.

Troubleshooting steps may change by the manufacturer, type of communication system, number of wires, and colors of communication system wires.

Symptoms of fault code U0122

Check Engine light illuminated.
Light signaling Anti-lock Wheel System
Unstable ABS
Traction problems.

Causes of OBD2 U0122

The reasons that lead to the setting of the U0122 OBD2 diagnostic code are:

The ECM or PCM may have an open or shorted circuit to the ground.
The CAN bus could have damage to its wiring causing a short to ground or power.
A control module may be defective.

Possible solutions of the DTC code U0122

The steps to correct the DTC U0122 OBDII code are as follows:

When starting the diagnosis, it is necessary to consult the TSB.
Inspect all wiring that is related to the ECM/PCM. Look for poor connections due to burns or wear and make corrections.
Check that the ground circuit and Control Area Network power circuits are functioning properly. If inconsistencies are detected due to electrical components in poor condition, proceed with the respective repairs.
Verify that all VDC fuses and ground connections are not defective. Correct it as necessary.