Did you set it up using tune ecu? Theres a procedure for that, its not a replace and ride thing. You have to know what are the numbers, you need tune ecu for this. Normally check those numbers before changing part.
try clearing the codes to see if they come back.
might check the voltage to see if it has the 5 volts reference voltage
with tune ecu you can check to see what it is doing.
I experienced P0638 once, just appeared by itself once although it was after a couple of roll on drag races.
The butterflies were meeting resistance when turning, and loosening the 2 fixing bolts of the sec throttle stepper motor, in order to move it slightly so the resistance went away, fixed the issue.
TuneECU used to clear the code.
Never had it again, and the throttle has been used vigorously many many times since
Did you set it up using tune ecu? Theres a procedure for that, its not a replace and ride thing. You have to know what are the numbers, you need tune ecu for this. Normally check those numbers before changing part.
Thank you for the reply. I'm not familiar with the TuneECU. I have a Triumph Engine Management Diagnostic Kit. I will try and see if I can use it to fix issue.