The check engine light in your 2001 Subaru Forester comes on when the on board diagnostic computer generates a fault code related to the hatchback's emissions control system. This, in turn, causes the check engine light to come on. You can have the on board diagnostic computer scanned at most auto parts stores for free, and that will tell you what is wrong with the Forester. After fixing the problem, you need to reset the check engine light.
Open the fuse panel cover by pulling down on the Forester's fuse panel cover with your fingers. The fuse panel is under the steering column in the driver's side foot well. It has a long, rectangular, plastic cover.
Turn the ignition key to the "run" position.
Pull the fuse for the Forester's electronic control unit, or ECU, using the fuse pullers in the fuse panel. Use the fuse diagram on the underside of the fuse cover to locate the fuse for the ECU.
Wait five minutes and reinstall the ECU fuse. The check engine light will reset itself.