There are about 20 possibilities for the cause of the CEL.
Without knowing a code about all you can do is check the area of the filters to see if you knocked any wiring off sensors on the engine while doing the work.
Did you drive the coach ? Did the " Stop Engine light " come on ?
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.