I see people spend sums of money to acquire OBDII scanners as if that’s a fool proof alternative or substitute for quality technical care. Without a doubt, the D.I.Y (do it yourself) curve has been on a steady decline over the years, with this reality what do you think has been a quick ascent? Naturally, the need for expertise technical abilities to deal with a much slimmer range of cars is the order of the day. Gone are those days you easily could save a whole lot of money by being technically savvy. Personally, I don’t encourage D.I.Y practice for newer cars especially when it comes to unconventional/complex maintenance activities that might require replacements and special knowledge of a specific car.

On the other hand this is not to say that simple activities like tyre swapping or fuse replacement have become more complex and hence requiring specific expertise. That’s the more reason I came up with a list by comparing the honourable D.I.Y practice as it were in the past and the new limits imposed by the type of cars manufactured of recent.

Cars are generally more compact: Ford early this year released a 3cylinder, 1litre turbocharged engine which produces almost the same power as a 4cylinder 1.6 litre naturally aspirated engine and in some new commonly available sub-compact cars, removing the wiring harness from battery heads would require uncoupling quite a number of units to access the battery. The new order of the day is ‘lighter and greener’; hence, in most cases, only compact designs make it to factory floors for final production. This has led to unconventional placements of some car parts which can easily discourage a non-professional.

Electricals are more sensitive: Before now 12volts used to be the order of the day, but these days you have circuits with voltage ranges as low as 0.5volts equipped with relays and low resistance wires. The very solid presence of E.C.Us (electronic control units) has improved efficiency of cars generally and this isn’t without a little spike in the complexity of automobile electronics. Another fact worthy of mentioning is that these electrical/electronic components are now fused with areas of cars which were once wholly mechanical systems. What this means is that for you to start messing around with a bunch of wires you need to understand their relevance and how they enhance the role of the base mechanical system/component you might have been well familiar with.

Proper tools expensive to procure:[/b]Back in the day, one of the most sophisticated tools one needed for complex D.I.Y practice was may be timing lights (xenon) which weren’t that much expensive to come by. But these days, tools are more complex and expectedly more expensive; from an economic standpoint it doesn’t make much sense spending so much when you don’t intend using for professional practice which is supposed to yield income afterwards.

[b]Wrong interpretation/false assumption of OBDII codes: This happens to be the commonest reason you have to leave your car for the pros if you are not up for it. As it was clearly stated in a previously posted article, OBDII scanners are more of guiding tools as opposed to misconceptions surrounding the existence of these diagnostic tools as point-blank solutions to any car problem.
:source:http://www.autobaseafrica.com/things-that-can-go-wrong-in-modern-d-i-ydo-it-yourself-practice/