How to replace a sensor ay temp in a 2003 suburu outback limited Is there a diabram

Try inspecting areas around the water pump. You should see a lead wire going to the temp sensor someplace in this vicinity.
Call the dealer and have him fax/email a exploded drawing of the sensor and its location.
You can always go to a auto parts store and purchase a Clymer manual on your vehicle and this drawing and steps to remove and replace sensor will be there.
Cheers,
TF