• Check Engine Light is on
• Vehicle may not start
• Various warning lights on the dashboard
• Faulty control module
• Open or shorted CAN bus wiring
• Faulty CAN bus connectors
CAN bus: A robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other.
Control Module: An electronic device that manages various systems in a vehicle.
• U0100
• U0121
Your car's computer is having trouble talking to one of its parts. It's like when your phone can't connect to Wi-Fi.
U0640 indicates a communication error between the vehicle's control modules.
The U0640 code is set when the vehicle's control module cannot communicate with one or more of the other modules on the Controller Area Network (CAN) bus. This can be due to a loss of communication or a malfunction in the network.
• Use a scan tool to check for other related codes.
• Inspect CAN bus wiring and connectors for damage.
• Test the control module for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty control module.
• Clear the codes and test drive the vehicle.
• OBD-II scan tool
• Multimeter
• Wiring diagram
$150 - $1200, depending on the specific issue and labor costs.
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect and maintain vehicle wiring.
• Avoid water exposure to electronic components.
• Ensure proper installation of aftermarket devices.
Communication Error
• Have your vehicle inspected by a professional.
• Avoid driving the vehicle if it exhibits severe symptoms.
• Keep a record of any recurring issues.
Check with your vehicle manufacturer for warranty coverage on electronic components.
U0640 has become more common with the increased use of electronic control modules in modern vehicles.
Moderate – It should be addressed soon to prevent further issues.
Driving with a communication error can lead to unexpected vehicle behavior and should be addressed promptly.
• Vehicle in park or neutral
• Engine running
The control modules are typically located under the dashboard or in the engine compartment.
Q: Can I drive with a U0640 code?
A: It's not recommended to drive for long periods with this code, as it may affect vehicle performance.
Q: Will a U0640 code clear itself?
A: The code may clear if the issue is resolved, but it's best to use a scan tool to ensure it's properly cleared.
