U2602 – CAN Communication Bus Off.

The ODBII code U2602 indicates a communication issue on the Controller Area Network (CAN) bus, specifically that a device or module has gone “off” or is not communicating properly within the network.

The severity of ODBII code U2602 CAN Communication Bus Off is moderate to high.

Common Causes For: U2601 Communication Bus Off.

• Faulty CAN bus wiring or connectors
• Defective CAN bus module
• Short circuit in the CAN bus
• Open circuit in the CAN bus
• Interference from other electrical components
• Faulty or damaged sensors communicating over the CAN bus
• Software or firmware issues in the control modules
• Low battery voltage or poor power supply to the modules
• Grounding issues in the vehicle’s electrical system
• Corroded or loose connections in the CAN network

Common misdiagnosis for U2602 CAN Communication Bus Off.

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Faulty CAN bus transceiver
• Incorrectly diagnosed sensor issues
• Power supply issues
• Faulty diagnostic tools or software errors
• Misinterpreted DTCs related to other systems

Common Troubleshooting Steps

The OBD-II code U2602 indicates a problem with the CAN (Controller Area Network) communication bus, specifically that the bus is “off.” This can lead to communication issues between various modules in the vehicle. Here are some common troubleshooting steps to diagnose and resolve the U2602 code:

• Check for Additional Codes: Use an OBD-II scanner to check for any other related trouble codes. This can provide more context about the issue.
• Inspect the Wiring and Connectors: **Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the CAN bus.
• **Loose Connections: Ensure that all connectors are securely attached and free of corrosion.
• Test the CAN Bus Voltage: Use a multimeter to check the voltage levels on the CAN High and CAN Low wires. The typical voltage levels should be around 2.5V when the bus is idle.
• If the voltage is significantly off, there may be a short or open circuit.
• Check for Short Circuits: Inspect the CAN bus wiring for any shorts to ground or to other wires. This can cause the bus to go offline.
• Inspect Modules on the CAN Bus: Identify all modules connected to the CAN bus and check for any that may be malfunctioning. A faulty module can disrupt communication.
• Disconnect each module one at a time to see if the code clears or communication is restored.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the CAN bus communication, such as alarms, stereo systems, or other electronic devices.
• Perform a Network Test: Use a professional scan tool capable of performing a CAN bus network test. This can help identify which module is causing the issue.
• Inspect the Ground Connections: Ensure that all ground connections related to the CAN bus are clean and secure. Poor grounding can lead to communication issues.
• Check the Battery and Charging System: A weak battery or charging system can cause voltage fluctuations that affect the CAN bus. Ensure the battery is in good condition and fully charged.
• Clear the Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.1
• Consult Service Manual: Refer to the vehicle’s service manual for specific troubleshooting steps and wiring diagrams related to the CAN bus system.1
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician with experience in automotive electronics. By following these steps, you should be able to identify and resolve the issue causing the U2602 code.