Forscan plays two different roles in terms of what it does. First, it's like a really capable code reader that can reach into every module in your car and tell you what's going on. You can clear codes, you can run diagnostics, you can run service cycles like ABS flush or diff cooler pump.
I’ve used FORScan to change settings on my 2018 F-150 like the double horn honk and others but I was not aware you can run diagnostics. I am trying to see if I can figure out why my MPG has dropped 2-3 MPG lately. I called the Ford dealer and they said they could run diags for $139 so is there a way to use FORScan to do this? If so, can you give me some direction.
That's pretty straightforward. Plug in your OBD dongle, hook up to Forscan and see if any codes are set in any module - most likely the ECU, but there could be others. If there are no codes, then your F150 is running properly and any decline in fuel economy isn't caused by an engine or transmission fault. The reason this works is that Ford has programmed every module to detect deviations from normal, for instance, if the trans is slipping, the ECU will know that. It may not turn on a check engine light, though, so your scan for codes will turn up the problem and set you on the path to fixing it.
They are super cheap.