The Memoscan U581 Universal Car Fault Code Reader is a small plug-in CAN-BUS OBD2/EOBDII reader which you use to read and reset your car’s computer fault codes. There’s a fair few of these around on the market currently, but this looks like the most comprehensive of the bunch at this sort of price, especially since it displays explanations of the codes as well as just the cryptic numbers. I’m guessing it will pay for itself the first time you use it instead of slogging over to your nearest vehicle repair-person in a panic. Priced at £67.00 or $98.80.
You just plug straight into the vehicle’s diagnostic socket (in the interior and from the comfort of the driver’s seat) and start using it, it’s that simple. Read fault codes, reset fault codes and the check engine light (MIL) You need nothing else! Not even batteries as it powers off your car’s diagnostic socket. Not to be confused with the cheap code readers you can buy from stores – they are nothing more than an overpriced LED in an empty box and utterly useless!
For a little less money, if you have a laptop then this:
makes a good option. I use it on my cars for tuning in addition to resetting/diagnosing errors since it gives you a live feed to all the monitoring data.