My engines runs rough but I can't get any codes to help me out. I disconnected egr wires, then my 02 senser wiring just to see if it would throw a code and it didn't. Service engine light does work, but it only gives me the 12. Shouldn't it throw codes with those two components disconnected? Any thoughts/suggestions?

 

it should, some times you have to let it run 4 a lil 4 it to throw a code. maybe ecm problem