The F5 code means that the range door isn't latching properly (for some Whirlpool ranges). Check the latch when the oven is cool. If it is loose, tighten the screws that hold the latch. Try opening and closing the door to see if the latch is clicking shut properly. Then unplug the range for 30 seconds to a minute to reset the unit. If the error clears, you're done.
If the error persists, clean the latch area. With the oven not in use, rub the latch area with a cloth that you dunked in hot water and wrung out the excess water. Then dry with a paper towel.
If cleaning doesn't help, the latch probably needs to be replaced.
I hope this helps. Please give me the model number of your range for additional ideas. Whirlpool has the user's manuals for most of their appliances at their site. See http://www.whirlpool.com/custserv/index.jsp
and the Manuals and Literature search box.