Sometimes the Check Engine Light illuminates because the computer detects misfires. Subaru released an improved spark plug wire set to solve the problem. The ignition coil should also be inspected for carbon tracks or short circuits between the contactsGoogle+
Car Problem Reports
Subaru Impreza Outback Sport Improved Spark Plug Wires for Misfire Issues
Subaru Impreza Outback Sport Problem
Engine Affected: 2.5L 4 Cylinder
Visitor, 2009 Subaru Impreza Outback Sport, 2.5L 4 Cylinder, 104,000 mi
Check engine light came on while driving and showed cylinder 4 misfire. Leaking spark plug gasket.