U0401: Invalid Data Received From ECM/PCM "A"
A module is receiving data from the engine control module, but the data is not valid.
Normal risk
Have it checked soon.
Short answer · Can I keep driving with U0401?
Usually yes if the car runs normally, but have it diagnosed.
What does U0401 mean?
U0401 is stored when a module receives messages from the engine control module that are missing values or implausible.
What the car does when the code is set
The receiving module ignores the invalid data. Functions that rely on it may be limited and warning lights can come on.
How the system works
Modules check incoming data for plausibility, for example value range and message counters. When the data is present but not plausible, they store an invalid data code naming the sending module.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Fault in the module that sends the dataFor example a sensor fault inside or connected to that module.
- Network interferenceWiring problems can corrupt messages.
- Software mismatchModules with incompatible software versions.
- Low battery voltageUnstable voltage can corrupt data.
How it is diagnosed
- Read codes in the sending moduleCodes stored there often explain why its data is invalid.
- Check battery voltageMake sure supply voltage is stable.
- Check for software updatesA dealer can check for technical service bulletins and updates.
- Test the networkA workshop inspects the wiring if the data keeps arriving corrupted.
Questions about U0401
Is U0401 the same as U0100?
No. With U0401 messages arrive but the data is invalid; with U0100 they do not arrive.
Why does one module report another module’s data?
Modules share data; the receiving module notices when values are missing or implausible.