Engine light came on after I put on new ceramic headers?

I have a Honda Civic lx 2005 1.7l sedan. I'm thinking because the factory made manifold came with a Catalytic converter and the headers i put on doesn't that the light came on. Someone suggested that i get my car's computer reprogrammed but i don't know where?

Hi, the catalytic converter is in the exhaust pipe not in the manifold. But there may have been a O2 sensor in the stock manifold and you may have to add one down line of the header. You would need to take it to a shop to have it reprogrammed.

That's one of the problems with trying to "modify" a vehicle that's not made to be changed from factory parts… Your vehicle will not pass an emissions testing now either