I bought this plug in obd-II bluetooth module and used it with the Torque app on my cell phone. Basically lets you turn your phone into a display for things like engine temp, throttle position, etc. You can also clear trouble codes

more info here: http://www.dealextreme.com/p/elm327-...r-dongle-16921

$40 shipped

 

can u use with iphone?

 

Yes, but the app most iPhone people use is called Rev. Same concept different developer: http://youtu.be/OAS3EG17Mwo

 

bump = $30 shipped