I have a 2013 sti and I had a pro tune and everything was fine now I noticed that my valve covers are leaking oil changed spark plugs and I am getting feedback knock up to -8.0 at low rpm is this due to the valve cover leaking
It's more likely due to the plugs or the procedure of changing them. No CELs? Did you replace the plugs with identical new plugs and did you check the gaps? Are the annoying little clip thingies all attached so your coils are secure?