I am thinking of getting a OBD2 reader for self-diagnosis and have a few questions:

• Is it best to go for a USB one that plugs into a laptop? Or a stand-alone one?
• Are there any brands/price ranges/websites I should avoid?
• What is the difference between ELM327 and STN1110? And which does the Fiesta MK7.5 require?

 

Depends what you want it for really.  

Bluetooth and a phone app is ideal for keeping in the car at all times, but not as in depth as full laptop programmes.

Cable and laptop is safest if you want to rewrite modules but obviously not convenient if you break down without the laptop to hand.

Ford specific software is far better than generic OBD readers.  I've got a decent standalone generic reader but rarely use it tbh.  FORScan is much better for Fords and I've got other specific ones for other makes.

Not sure if there's anything like ELMConfig or Focccus available for the mk7.5 fiesta yet, but those are fantastic programmes for the Focus'.

I bought one off ebay, junk and didn't work, apparently a lot of fakes on the bay. I bought one here https://tunnelrat-electronics.fwscart.com/ and it works a treat. I got the WiFi + USB Modified ELM one so it gives me the choice of using it via mobile or usb to the laptop.