You can buy dirt-cheap (around a fiver) devices that link via blue tooth to your phone, tablet or laptop which show you a lot you need to know. for example
http://www.lightinthebox.com/hhobd-...interface-adapter-live-data_p808201.html but there are many other similar products. They work well, and you can download free software which interprets the fault codes found by these devices.
Many of the fault codes are industry-wide and are well known, but unfortunately a lot more are model or manufacturer specific and the manufacturers can be very secretive about these.
I've found these devices are much better than the scanners that come with a display, because you can get up-to-date lists of what the codes mean over the internet, and you may end up doing searches to find what a particular code means if it is something the manufacturer is trying to keep secret anyway. The display on a laptop or a tablet is much better than scanners with cables, and mucking about with cables is a pain. I bought one and having used it to solve my problem gave it to someone who I think still has it.