There are diagnosticians and there are diagnosticians when it comes to auto repair.
Some of the times second best will just not do when it comes to say electrical problems on your vehicle and your local standard auto garage just will not do and you have to call in or visit a specialist or perhaps more in depth diagnostic auto repair shop in your area.
Still in many cases it many not be that the auto repair shop with the great established name in your area (and generally a higher fee) is even better or more experienced than the smaller shop but rather that they either have more specialized and advanced tools or simply have the time to examine the problem thoroughly and fully with out distraction.
In other cases it may be simply that most of the variables and issues have been worked out before.
Most of the workup has been done, a lot of frustration and frustrating time spent.
The next person, mechanic of technician just has to start from square one once again, go though the paces and just do it once more time, to completion and fruition.
Thus voila the problem is identified and thus solved.
The last auto diagnostic person in is thus a hero.
Yet one might ask from the very beginning why is auto and engine diagnosis so important to begin with.
It can be said that if any mechanic can not or does not know in essence how to find, locate and challenge automotive, engine and motor difficulties and problems then all in all you are wasting your and their time, money and effort.
Its all money and time thrown down the drainpipe.
Reliability is key.
If you or your mechanic can not identify motor or engine problems you ultimately will have not solved the problem at hand fully, your vehicle will not be properly or fully repaired and ultimately neither you nor your family will have neither pleasant nor economical driving experience.
Simple as that.
Pleasant driving and motoring.