I have a 2010 Mercury Mariner Premier, 197k miles, automatic transmission, but it only had one key when I bought it. I've heard from some of my colleagues at work that I can't use a key that isn't a transponder key with it, including remote key fobs. Is that true, or is there a way to be able to use a remote key fob with a separate key as opposed to the all-in-one transponder key?
Usually you can get a transponder key without a remote.
I’d really avoid getting an aftermarket immobiliser/alarm system if you want it to work reliably..
You're best going to the dealer & ordering another OEM key.
It depends truly only on your exact car - I think it's worth trying.
On Ford Focus, I have a transponder only key and it's enough to open all doors and drive the car.
But it can not be used to close all doors or open the boot because that's the way Ford programed it on this specific model, year and trim.
Someone I know with the same car model year and trim can actually do a lot more with his key. So yeah, there's no real way to know...
