I bought a 2000 Chevy Tracker from a friend that doesn't have eCheck, so he didn't know the Service Engine Soon light was an issue. The codes from Auto Zone are P0455 & P0440, both of which read "Defective or loose fuel cap". Well, it leaked fuel, so we replaced the fuel tank. While doing the fuel tank swap, the goose-neck for the fuel intake was... well, obliterated. It was so rusty, that just disturbing it caused it to disintegrate. Well that certainly explains the Service Engine Soon light. However after replacing it, the codes do not automatically clear.

Is there a way to force the codes to reset, &/or clear them? I'm looking online & seeing responses such as "After resetting the codes..." but I don't see a way to force a reset.

Broke down & removed the negative battery terminal. Guess I'll wait & see if it comes back :P

Autozone will check the codes for free and, if you can show that you've fixed a problem, they'll generally reset the computer once or twice. After that, they tend to check only.

Yup, have a local store set/reset it. Or buy a tool to do it yourself (<$30 online).