you think the CEL comes on for no reason? It comes on to tell you that something isnt working right with the ECU/Car
So lest for instance say that your car has exhaust changes or power mods added to it and you dont get an ECU remap. What will happen is the check engine light will come on to warn you that there is a problem detected.
Do..............realise that when the CEL appears the ECU will retard itself to a certain extent to compensate or safeguard being the better word and ensure the thing doesnt break.
Yes, people do run about with decats, up pipes, down pipes, new turbos and get away with it for years. They are lucky in some respects cos their car isnt breaking, but unlucky on the other cos they never unleash the power benefits and safe running of their pride and joy by saving a few pounds.
Go get CEL fix and put the light out. Take the strereo out as well so you can hear the pistons slapping off the underside of the bonnet, the rods popping out or the big end going.
I have a car that has been mapped from teh day it was around 300bhp until now which is stretching out towards 450bhp and know the other people that have powerful cars and they are ALL SAFE
I also knew a guy that did crazy things and mods without safety and it cost him a brand new 54plate WRX. I had to sell the car after that.