I've got an 04 6 speed. It starts and runs great. No hesitation or bogging down yet I see P0301 Rotor 1 misfire detected. I tried swapping the order of the coils to see if the problem followed to Rotor 2 but no dice. There is one thing that seems out of place and thats a defauler plug extension thing. This problem has been constant before and after new coils, wires and plugs.

The P0661 is? Is this a dirty SSV valve error or are we talking about the three solenoids near the firewall? Could this be causing the other CEL messages?

I'm seeing that U1900 is either a bad can bus or injector malfunction. Are maybe the injectors dirty and are causing some misfires???

Any help greatly appreciated.

 

Defouler plug extension? There should be no such thing, unless I'm not understanding what you mean.

P0661 is one of the relays.

U1900 i have no idea. Clear it, see if it returns.