I have a code that says my #4 injecter cycle open, misfire.

Injector doesn't stop spraying. What kind of wiring problem can I check into myself, between #4 and ecm. Will a dealer scanner tell me about a wiring problem or a bad ecm?

Ok, what kind of scan tool do you have, like a Snap-On Modis?

I checked tonite and the injector plug has constant power to the injector. Not good. I just used a Advanced Auto scanned, the code is PO204. With a Snap On scanner what else can he look for beside the PO204 code?