I don't see how the dealer wouldn't be liable for the CEL. Isn't there some sort of safety standard that their cars have to meet before they can sell it? IE: when you turn the key to the "ON" position without starting the car, all the lights on the dashboard should light up to test them. I would figure this is a big safety issue if the ABS/Airbag/CEL/TCS lights don't come up.

Sucks about your luck with the shitty car. You should know better next time about running a Carfax and maybe taking it to a 3rd party mechanic next time.