I have a 2004 Toyota Highlander

The 44 codes are evap codes. one of them is for a large leak. quite often just not a tight gas cap. try that first and clear the codes and see if they come back. If they do, it could be a purge solenoid.

OK. Then, how do I clear the codes?

on some vehicles, you can simply unhook the battery for a minute or two, but if I were you I would purchase an inexpensive scan tool. that way you can clear the codes yourself.

Thank you so much! You have been fantastic!

Unhooking the battery on newer cars can lead to problems. The correct way to clear codes is with a code scanner.

F-o-r is right of course. On newer cars presets and anti- theft problems can occur. You can use a code keeper device but most folks don't have them. Code reader is always the best option. I stand corrected.