>>>do you know what a 13mm ...
>
>More to the point, what's a mm?
>
>(yeah, bad joke)
>
>Amazing how tech goes around. By the turn of the century it was getting tough to self-service a car because so much of it's controlled by chip, needing special $10K service computers to access diagnostics. And then... in recent years devices costing $30 came out that can read most vehicle diagnostics. Of course people bought their own to give them leverage over service shops claiming this and that needs replacement. Now I see bluetooth devices with no screen that interface to your phone, for as little as $5.
>
>All this, just before the true electric car revolution with only interval servicing needed on a vehicle with a few dozen moving parts that can be expected to last 500,000km (what's a km?!)

Yep I got myself one of those handy little bluetooth OBDII readers and an app for my phone to use it. Think I paid 4 bucks for the device and spent like 4 bucks on the software. There are free ones but of all the ones I've played with this one seems the best
https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en
..and I have a few for my widows laptop that are even better.
It's all pretty cool and all - but of course it's only going to help you find problems that are stored in the ECU --- but for most purposes and most people it's good enough.

Of course the electric cars will be better -- less moving parts :)