U1825 – Module Communication Failure

The ODBII code U1825 indicates a “Module Communication Failure,” meaning there is a problem with communication between the vehicle’s control modules, often due to a wiring issue, a faulty module, or a network problem.

The severity of ODBII code U1825 is moderate.

Common Causes For: U1824 U1824: “Module Communication Failure”

• Faulty wiring or connectors
• Failed or malfunctioning control module
• Corrupted software or firmware in the module
• Poor ground connections
• Intermittent communication issues
• Electrical interference
• Damaged or corroded pins in connectors
• Battery voltage issues
• Faulty CAN bus communication
• Incompatible or missing modules in the network

Common misdiagnosis for U1825 U1825: “Module Communication Failure”

• Faulty wiring or connectors
• Defective control modules
• Software issues or updates needed
• Battery or power supply problems
• Grounding issues
• Intermittent communication faults
• Incorrectly configured or programmed modules
• Corrupted data or settings in modules

Common Troubleshooting Steps

The OBD-II code U1825 indicates a “Module Communication Failure,” which typically means that there is a problem with communication between the vehicle’s control modules. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other 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 Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear.
• Check Power and Ground:
• Ensure that the affected module(s) are receiving proper power and ground. Use a multimeter to check voltage and ground continuity.
• If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses or damaged wiring.
• Test the Affected Module:
• If possible, test the affected module to see if it is functioning correctly. This may involve bench testing or swapping with a known good module.
• If the module is faulty, it may need to be replaced.
• Check for Communication Issues:
• Use a scan tool to check if the affected module is communicating with other modules. If it is not, there may be a communication bus issue.
• Inspect the CAN (Controller Area Network) bus wiring for shorts, opens, or interference.
• Look for Software Issues:
• Ensure that the vehicle’s software is up to date. Sometimes, a software update can resolve communication issues between modules.
• If applicable, perform a reset or reprogramming of the affected module.
• Inspect for Environmental Factors:
• Check for any environmental factors that may be affecting module communication, such as water intrusion or excessive heat.
• Perform a System Reset:
• Disconnect the vehicle’s battery for a few minutes to reset the modules. Reconnect and see if the code reappears.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to module communication.
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle and its systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1825 code.