U2070 – Control Module Communication Bus Off.

The ODBII code U2070 indicates a communication issue where a control module is not able to communicate on the vehicle’s communication bus, often due to a fault in the module itself or a wiring issue.

The severity of ODBII code U2070 is typically considered moderate to severe.

Common Causes For: U2069 Control Module Communication Bus Off.

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Communication bus short circuit
• Open circuit in the communication bus
• Interference from aftermarket devices
• Software issues or firmware corruption
• Low battery voltage or power supply issues

Common misdiagnosis for U2070 Control Module Communication Bus Off.

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply problems
• Intermittent connection issues
• Other communication bus faults (e.g., CAN bus issues)

Common Troubleshooting Steps

The OBD-II code U2070 indicates a communication issue between control modules in a vehicle, specifically that a control module is “bus off.” This typically means that the module is unable to communicate on the CAN (Controller Area Network) bus due to a fault. Here are some common troubleshooting steps to diagnose and resolve the issue:

• 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 Wiring and Connectors: Visually inspect the wiring and connectors associated with the control modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the CAN bus wiring, which typically consists of a twisted pair of wires.
• Check Power and Ground: Ensure that the affected control module has proper power and ground connections. Use a multimeter to verify voltage and ground continuity.
• Test the Control Module: If possible, test the control module in question. This may involve bench testing or swapping with a known good module to see if the problem persists.
• Check for Short Circuits: Inspect the wiring for any short circuits to ground or to other wires that could cause communication issues.
• Look for Intermittent Issues: Sometimes, communication issues can be intermittent. Monitor the vehicle’s performance and check for any patterns that may indicate when the issue occurs.
• Inspect Other Modules: If multiple modules are involved, check the other modules on the CAN bus for faults. A fault in one module can affect communication across the entire bus.
• Check for Software Updates: Verify if there are any software updates available for the control modules. Sometimes, manufacturers release updates to fix known communication issues.
• Scan for Bus Activity: Use a scan tool capable of monitoring CAN bus activity to see if there are any abnormal signals or if the bus is functioning correctly.
• Clear Codes and Test Drive: After performing 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 diagnostic procedures related to the U2070 code and the control modules involved.1
• Seek Professional Help: If the issue persists after performing these steps, consider seeking help from a professional mechanic or automotive technician who has experience with CAN bus systems. By following these steps, you should be able to identify and resolve the underlying issue causing the U2070 code.