U0401 Code: Invalid Data Received from ECM / PCM “A”

Is your check engine light on? Using a scan tool can help you identify your vehicle’s problem. If the U0401 code has been triggered, this article will inform you about the code’s definition, common causes, and common symptoms.

What Does the U0401 Code Mean?

Diagnostic trouble code U0401 stands for Invalid Data Received from ECM/PCM “A.” This code is logged when modules on the data network are receiving implausible data from the ECM/PCM. Modern vehicles use a data network that allows vehicle control modules to communicate with each other. These control modules expect to receive a specific type of information from related modules.

Note: The definition of the U0401 code can be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the U0401 Code?

The U0401 code can be triggered by the following problems

• One or more faulty sensors causing the PCM to send invalid data
• A dead battery or charging system problems
• Circuit issues, such as a damaged wire or poor connection
• PCM problems
• Data network problems

What are the Common Symptoms of the U0401 Code?

The P0401 code can cause your vehicle to show the following symptoms:

• Illuminated check engine light
• Vehicle refuses to start
• Vehicle enters “limp mode”
• The traction control system or stability control might get disabled

How to Diagnose the U0401 Code

While the U0401 code might have a list of common causes, you will still need to verify what specifically is wrong with your vehicle. Keep in mind that the steps for diagnosing this and other trouble codes may vary depending on your vehicle specifications.

Diagnosing DTCs requires a lot of technical knowledge and may need specialized tools. If you don’t think you’re up to the task, you shouldn’t hesitate to let a professional mechanic do the job for you.

How to Fix the U0401 Code

Attempting to fix the U0402 code can be difficult especially if you don’t have the right tools and knowledge. If you have any doubts, feel free to consult a trusted mechanic. If you think you have the automotive know-how to work on your vehicle, make sure to follow the right steps because repair procedures can vary greatly between different makes and models.

It’s vital that you find reliable sources and how-to guides. You can try checking guides like those from Chilton or an ALLDATA single vehicle subscription. You can also consult your vehicle manual, as they might have important information that can help you.