You should not have a check engine light unless something is wrong, it may blink or come on at full throttle during a very hard run on the higher settings if you are over boosting and don’t have a map sensor fooler or if the ICP or EBP isn’t happy. What kinda code reader you using? If the light is coming on then there should be codes stored. Some code readers cannot properly read powerstrokes, they are slightly different than normal OBDII gassers.