2012 G37 journey sedan with 90k miles.
My car all of a sudden started running really rough. I opened the hood to find an exploded rad hose. I fixed it thinking that would fix my problem but nope. I went to autozone for the check engine light where they showed me like 6 codes getting thrown. Here is a picture of the printout https://ibb.co/86w9h3N

About 3 months ago I had a leak in the valve cover that I got professionally fixed. while he was there I had him change the sparkplugs but not the coil packs. Im hoping one of the coils packs just went bad since the car is at 92k miles. I ordered it and will be replacing it tomorrow.

But that theory may be wrong because im also getting code P0300 thrown (multiple misfires), could a single faulty coil pack cause this multi-misfire code to be thrown?

Or, could it possibly be a bad seal in the valve cover from the repair I got done?

 

Sometimes a single cylinder misfire will set off a multiple random misfire code also.

I would first try to take the coil pack from cylinder 3 and swap it with cylinder 1 and see if it follows.

Make sure the bater terminals are conected well and there isn't any corrosion.

reset the code and go from there, see what new codes come back. Maybe check the freeze frame to see the condition that caused the code, is it a lean condition or rich to make the misfire.