Car shudders under load. Can rev in park to 3000-4000 rpms nice and smooth. Stock Calibration, never flashed.
Underload it stutters, then throws the following codes:
U0401 Invalid Data from ECM
U0100 lost communiction with ECM
P0300 Random Misfire.
U0401-codes.jpg
Only oddity I saw in the log was the Vehicle Speed (SAE, logged) didn't match actual vehicle speed (log showed max 6 mph and we were easily at 40 mph)
Voltage on Control Module and battery are good.
What would cause U0401? Its a new one to me.