Would it be rude?
 

To turn up to view a car for sale with a diagnostic laptop under my arm?:shrug:

Read countless times that people have bought cars with warning lights messed about with, and even concealed by having paper stuffed into the binnacle holes.:eek:
Surely no one would mind if they were a genuine seller?:shrug:

I would. I might be left with a bricked, unsellable car. :duh:

If its my car.......your not plugging anything in ! LOL

:duh: :getmecoat:

You could turn up with a gas axe as far as I'm concerned - Once you've paid for it (the car) you can do what you like with it. But don't cause a nuisance outside my house.

http://www.pistonheads.com/gassing/t...%3F&mid=201503

Personally I would say "no" unless you knew what you were doing. More because of a risk of you misunderstanding the results (e.g. BMWScanner will throw up loads of errors - because it's not really a BMW), than damaging the car.

I once went to buy a tractor unit and took a mechanic with me plus full diagnostics, if the seller is genuine I don't see a problem, however if you turned up at my house and wanted to plug a laptop into my car I would tell you where to go, better to test drive the car properly than start messing around with plugging things in, a good test drive will tell you lots.

I wouldn't bother, and view it as time wasting. If you come to buy a car from me, it is what it is. I will give you a cup of tea, and in return, I expect not to have my time wasted.

If I wanted to hook up a diagnostics tool, I'd give the seller the heads up in advance.
Let them know what you want to do, why you're doing it and the kit you'll use.

A genuine sellers biggest fear would be that you'll brick the car so you'll need to provide some reassurance on that front.

Worst case is they say no.