it's probably having no cat as stated.
but i dont know why you even considered just taking the bulb out.
thats a quick bandage, and doing those sort of things with DSMs will come back to haunt you later and make you give up like the many too weak or lazy to own a DSM in the first place. they end up selling the car right away and then proceed by spreading how unreliable it was, but really the only thing to blame was themselves..
but i'm sure you won't be turning out like that now will you..
go to autozone and rent a logger to see what the code is and fix it, they give you the money back after you return it, or find a friend who has one.
but if you really want to be ghetto and do as you suggested, you don't have to take out the dash, just remove the bezel around the cluster, then remove the cluster, then proceed to remove the bulb.