U2337 – CAN Bus Communication Failure

The ODBII code U2337 indicates a “CAN Bus Communication Failure,” which means there is a problem with the communication between the vehicle’s control modules over the Controller Area Network (CAN) bus.

The severity of ODBII code U2337 is moderate to severe.

Common Causes For: U2336 U2336: Control Module Communication Bus Fault

• Faulty CAN bus wiring or connectors
• Short circuit in the CAN bus
• Open circuit in the CAN bus
• Faulty control module
• Corroded or damaged connectors
• Interference from other electronic devices
• Low battery voltage
• Software issues or bugs in the control module
• Poor ground connections
• Damaged or malfunctioning sensors on the CAN network

Common misdiagnosis for U2337 U2337: “CAN Bus Communication Failure”

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Faulty CAN Bus transceiver
• Malfunctioning sensors
• Power supply issues
• Software glitches or updates needed
• Faulty diagnostic tools or equipment

Common Troubleshooting Steps

When dealing with an OBD-II code U2337, which indicates a “CAN Bus Communication Failure,” there are several common troubleshooting steps you can take to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect the Wiring and Connectors: **Visual Inspection: Look for any damaged, frayed, or corroded wires in the CAN bus network. Pay special attention to connectors and terminals.
• **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 should be around 2.5V when the bus is idle.
• If the voltage is significantly off, it may indicate a problem with the bus or a connected module.
• Check for Short Circuits: Inspect the CAN bus wiring for any short circuits to ground or to each other. This can cause communication failures.
• Examine the Modules on the CAN Bus: Identify all modules connected to the CAN bus (e.g., engine control module, transmission control module, ABS module).
• Check for any signs of failure or malfunction in these modules. A faulty module can disrupt communication.
• Perform a Network Test: If you have access to a professional scan tool, perform a network test to see if all modules are communicating properly.
• Some tools can also provide a “bus off” status, indicating if a module has been disconnected from the network due to a fault.
• Check for Interference: Ensure that there are no aftermarket devices or modifications that could be interfering with the CAN bus communication.
• Clear Codes and Test Drive: After performing inspections and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.
• Consult Technical Service Bulletins (TSBs): Check for any manufacturer-specific TSBs related to the U2337 code. There may be known issues or recalls that could apply to your vehicle.
• Seek Professional Help: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with CAN bus systems.Additional Notes:
• Safety First: Always ensure the vehicle is in a safe state before working on it, especially when dealing with electrical systems.
• Documentation: Keep a record of any codes, symptoms, and repairs performed for future reference. By following these steps, you should be able to identify the cause of the U2337 code and take appropriate action to resolve the communication failure.