U2104 Cadillac Code - Controller Area Network Bus Reset Counter Overrun

U2104 indicates a Controller Area Network (CAN) bus reset counter overrun, meaning there have been too many resets of the CAN bus communication, often pointing to potential communication issues between modules.

Common symptoms may include warning lights on the dashboard, communication failures between modules, erratic behavior in vehicle systems, or the vehicle not starting properly.

Possible causes include faulty wiring in the CAN bus, a malfunctioning control module, short circuits, or issues with the vehicle’s battery or power supply affecting module communication.

To diagnose U2104, start by using an OBDII scanner to confirm the code. Check for additional codes, inspect the wiring and connections in the CAN bus, and test the affected control modules for proper function.

If you have automotive experience, you can attempt to fix U2104 by inspecting the wiring and connections for damage, ensuring all modules are properly grounded, and resetting the system. However, complex issues may require professional assistance.

Ignoring the U2104 code can lead to further communication issues between vehicle modules, potentially resulting in more severe electrical problems, impaired vehicle performance, or complete failure of some systems.

While it may be safe to drive in some cases, it’s advised to address the U2104 code promptly to avoid further complications and ensure all vehicle systems operate correctly.

Repair costs can vary widely depending on the underlying issue, ranging from simple wiring repairs costing around $100 to replacing control modules which could cost upwards of $500 or more.

After repairs, clear the code using an OBDII scanner and take the vehicle for a test drive to ensure the code does not return and all systems are functioning properly.