Take it to autozone or whatever local FLAPS suits your preference and
ask them to read out the diagnostic codes. Post everything you get
from the code reader here, the codes are 5 characters long and begin
with one of four letters, with P being the most common. The second
digit will be either a 1 or 0, if it is a 1, it means that code is
vehicle specific, if it is a 0, that is a 'generic' OBD-II code. Also
keep in mind that a diagnostic code indicates a problem in a CIRCUIT,
not necessarily a sensor. Don't throw parts at the problem unless you
know for certain what is wrong.
Good luck with it.
Chris