Impreza WRX STI F4-2.5L DOHC Turbo (2007)
Spark Plug: Adjustments
ADJUSTMENT
Clean the spark plugs with a wire brush. Clean and remove the carbon or oxide deposits, but do not wear away ceramic insulator.
If deposits are too stubborn, replace the plugs. After cleaning the spark plugs, correct the spark plug gap using a gap gauge.
NOTE: Do not use spark plug cleaners, because the spark plugs are applied with iridium tips.