Answer to: engine light comes on after about half hour?please help help help I have a freightlner Century 2000 with a Detroit engine 12.7.. My truck is running but it is turning the checking engine light on and off. when it turns on, the truck kind of cough (make a noise like going stop) but is something quick. i get some white smoke every time.. about 600 miles ago I have the fault code 128. but it went away, now this problem is more often. I think it may be like a wire or a fuse moving or something like that, or maybe an injector.. What could the problem be??