My 2011 sport had the check engine light come on and the code was p0302. I looked up some old threads and it looked like could be a lose plug, or a bad, plug, bad coil and few other things.

My fit has 74k miles. Since getting to the plugs is pretty involved should I start by replacing them all? At the same time should I swap the coils and see if that moves the issue to another head?

Pretty much what is the order of operation for tackling this problem.

 

It's an easy, just time consuming, job if you remove the cowl. Other option is more difficult, but faster, to do it with the cowl in place.

Regardless, your issue is probably a loose spark plug, but once you've gotten to that point there's no reason to not go ahead and change the plugs. Use NGK or Denso Iridium plugs.

You can start it once the new plugs are installed and coils are back in place to see if there's any reason to move around coils. There probably won't be. I suspect you will find the coil boot on #2 to be sooted from a loose plug.

Here's the tough call to make...it's due for a valve adjustment at 90k miles and you'll be part of the way to completing that task when you have the cowl removed. Up to you but, if you plan on keeping the car long term, it may make sense to go ahead and do the plug change and valve adjustment now. Out of spec valves can also cause misfires.

 

Can you recommend a good spark plug?

 

I run Denso IK22's, but that's for performance reasons. It's a colder plug and our car makes better power with them. Runs smoother also.

 

Glad you caught it in time. Others have kept driving with the Check-Engine-Light (CEL) on and harmed the spark plug threads in the head (hot combustion gases erode the aluminum). Other's have needlessly replaced plugs & the coil packs when it was only a loose spark plug.

If you have a good mind's eye, and Ok left-handed, you can reach in on that side of the motor and replace the plugs without taking off the windshield wipers, etc, etc. What you can't do using that method is get a torque wrench in there. I did it the proper way once and two (2) plugs came loose again, so I reached in there, took off each coil pack, removed each plug, and put a dab of blue Permatex Threadlocker paste on each and then hand tightened. They have been good that way for +30,000 miles ('11 Sport AT with +85,000 miles).