Any Autozone, Baxters, NAPA, Pep Boys, wherever... they will let you use their (usualy nice) scan tool for free.
They might come out with you, to make sure you dont steal it... but the scan tool NAPA let me borrow had a big screen, like 10 inches, and could read any value from the car.
Would display realtime graphs of O2 sensors, intake temp, A/F mixture, throttle pressure, target RPM's and true RPM's (not sure what the diff was, the number was always within like 50rpm's close).
Obviously, it listed engine codes, and had full on-screen manual pages on what the code meant for most of the codes.
You could even force the engine into limp mode, where itll turn off O2 sensors, evap/egr functions, and just run basic stuff to keep the motor turning.
Was fancy fancy shit, the guy said that particular scan tool (from Snap-on) was like $10,000 :shock:
He said itd work on ANY car made after 1996, and on some cars a bit before that. It could also reprogram the ECU, it had a fucking floppy drive!!!!