Spark Plug: Cleaning
WARNING: This page is about a different car, the 2003 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
Clean the spark plugs in a sand blast type cleaner.
Avoid excessive blasting. Clean and remove the carbon or oxide deposits. When doing this, do not wear away the ceramic part.
If deposits cannot be removed, replace the spark plugs.