I have a Scan Guage II, works well, with one exception. If I leave it plugged into the OBDII port, it will work fine for days, then, without notice, it will shut off. will not reconnect right away, but does come back. I sent it back to the manufacturer for testing, they returned it, with not so much as a note, no indication of what they did or did not do. The unit still works the same.reads and clears codes fine, but not much sense using it as a trip meter, or for mileage , as it will fail on me.I just threw it in the tool box, and will buy something else.good luck