Below the steering wheel under the dash. If in doubt, check your owner's manual. It is invaluable for answering these kinds of questions when you can't wait for an answer on the internet. If you don't have one they are usually available on eBay.
Where is the knock sensor located on a 1999 Subaru Forester?
The ECU in a MY 1999 Subaru Forester is located at the upper left site of the engine under the air intake.
Subaru Forester was created in 1997.
The 1999 Subaru Forester air filter is located in the engine compartment inside of the air box. There is also a cabin filter located behind the glove box.
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 2004 Subaru Forester has 16 valves.
The 2006 Subaru Forester has 16 valves.
The 2011 Subaru Forester has 16 valves.