the fiat examiner smart is a diagnostic tool for use on all fiat group vehicles (assuming you have all the fittings to go with it, there are dozens). some independants have one (e.g. FAST in stockton) but generally they are a dealer only machine because they cost several thousand pounds and then you must subscribe to the updates which is not cheap.
an examiner can not detect faults, but it can be used for diagnosis in 2 ways. firstly you can read any stored fault codes in the ecu. this is what a basic code reader will do, but the examiner is the most reliable way to read and then understand fault codes because it has a database of the meanings all the fiat group specifc codes. the limitations of this code reading are based on what the ecu can detect as a fault. the ecu's strategy for fault detection is based on a permittable range for each sensor, any sensor that returns an out of range signal will trigger a fault code, the code will vary depending on what is wrong with the signal (e.g too high voltage, intermittent signal, short to earth etc). similarly a total loss of signal will trigger a fault code. fault codes can be cleared using the examiner, although this is not neccessary it is a good idea because it stops you getting fooled by an old code next time there is a fault.
obviously this leaves a great margin for faults to go unnoticed by the ecu. to deal with that you can use the examiner to read real time data with the engine running. the examiner will not detect faults in this way, the user needs to identify unusual data, the examiner simply displays it by communicating with the ecu. you can also do this with other similar machines, or even better do it the proper way and use an oscilloscope, but the examiner is an easier and quicker way for dealer staff to do it. for fault finding it does not have any functionality that can not be recreated at an independant garage using the conventional tools.
the examiner is able to access all modules on fiat group cars, including the airbag and abs. it is also used for key programming of fiat code system 2+ cars. for this type of situation you need an examiner, nothing else will do the job.
i want one for xmas please santa