2000 ford expedition xlt check engine light is on and OBD port does not read when plug into to check what's wrong help

Does light comes back on after it has been reset or just stays on?

What do you mean by "reset" ? It is always on each time it is started and stays on. The engine runs fine like always.

Have you read the code, if you have, what code number do you get? If not, take the car to any auto part store and ask them to read the code(s). Reset mean to have the computer memory cleared, once this is done, the check engine light goes off; it will come on again if the problem hasn't been fixed.

Okay so how do you clear the computer's memory is there something I can unhook or disconnect for a certain amount of time? Thank you for answering my goofy questions!

Do this: With engine off, remove the positive terminal in the battery, wait 5-10 minutes, replace terminal, tighten well, turn ignition to on, count to 10, this will give the computer time for a complete memory reset, then start the vehicle. If the light stays on or comes back it is a signal that the problem is still there.

Thank you Jorge you have been very helpful.