Thats for a misfire. If it popped up after you did this job, you may not have seated the plug or coil correctly Its impossible to give you a repair estimate based on a single code. There could be 1000 reasons for a misfire. No way to tell what work has to be done unless you take it to a shop first. If the code popped up after you changed plugs, you didnt do something right or one of the plugs was bad. Buy another plug and replace the one thats misfiring to see if its the plug