Network (U)
U0401: Invalid data from ECM/PCM
This code indicates that a control module has received invalid data from the engine control module (ECM) or powertrain control module (PCM). This can affect communication between modules.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Check engine light on
- Erratic engine performance
- Transmission shifting issues
- Reduced fuel efficiency
Common causes
- Module software mismatch
- Fault in CAN bus
- Low voltage from battery
How to check it yourself
- Check battery and charging system
- Inspect for other network-related codes
- Verify software compatibility of modules
- Inspect CAN bus connections
Can I keep driving?
The car can usually be driven, but erratic performance may occur. Address the issue soon to avoid further problems.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer