Spend the money to have it checked correctly or pay the piper later. While it might be something simple, it might just as well be something important. Get yourself a code reader or pay someone else who has one to read the codes. I would question the validity of a "Mobil mechanic did not have an diagnosis machine available to check for code diplay." ANY mobile mechanic worth his salt has the most basic working tools of his trade and a code reader is one of those BASIC tools. Heck, many of us on here are not even mechanics and we own them. Good luck....Dennis