Fault code U2002 – a step-by-step guide to diagnosing and fixing it

Error code U2002 is displayed and the check engine light is on - what does this mean?

The DTC U2002 is recognized by the OBD/EOBD system when a communication error occurs in the CAN bus network between different control units. This error code indicates a faulty data transmission between the vehicle's electronic modules. The exact designation may vary slightly for different manufacturers, but basically relates to network communication.

What causes can this error code have?

• Defective CAN bus cable
• Damaged plug connections in the network
• Faulty control units
• Corroded contacts on the connections
• Short circuit in the wiring
• Defective CAN bus terminating resistor
• Voltage problems in the vehicle electrical system
• Electromagnetic interference

What symptoms occur in parallel with error code U2002?

• Communication error: Various vehicle systems are not functioning properly
• Warning lights: Multiple indicator lights illuminate simultaneously
• Function failure: Comfort functions such as air conditioning or infotainment fail
• Starting problems: The vehicle is difficult or impossible to start
• Irregular engine running: Engine runs unevenly or stalls
• Shifting problems: Automatic transmission does not shift correctly

How can the U2002 trouble code problem be resolved?

• The elimination of the U2002 trouble code requires a systematic diagnosis of the network communication.
• Checking all CAN bus connections for tight fit and corrosion, cleaning or replacing the plug connections if necessary
• Measure the CAN bus cables with a multimeter for continuity and resistance values, defective cables must be replaced
• Check the on-board power supply voltage and check the fuses, replace weak battery or defective fuses
• Isolate individual control units by gradually disconnecting the connections to identify the defective module
• Replacing the CAN bus terminating resistors if they are out of specification
• Professional diagnosis with special CAN bus equipment and, if necessary, software update of the affected control units