You can't exactly pinpoint what caused the check engine light to come on without retrieving the trouble codes. Take your vehicle to AutoZone or similar auto parts store that offers free diagnostic scans and have the trouble codes retrieved and explained.
But first... check your gas cap. A loose gas cap can cause the Check Engine light to turn on. Really.
One reasons a Subaru Forester may overheat is because the radiator may need replaced. Another reason could be the thermostat.
105000 mi
Subaru Forester was created in 1997.
Subaru Forester has a timing belt.
The 2005 Subaru Forester has 16 valves.
The 2009 Subaru Forester has 16 valves.
The 2008 Subaru Forester has 16 valves.
The 2001 Subaru Forester has 16 valves.
The 2003 Subaru Forester has 16 valves.
The 2004 Subaru Forester has 16 valves.
The 2006 Subaru Forester has 16 valves.
The 2011 Subaru Forester has 16 valves.