Hi everyone,
So the story goes like this, I bought a 2006 2.0 sport a few weeks ago but it only came with a single keyfob, the previous owner informed me he lost the other key. After much reading on here and the web, I bought 2 more mitsubishi keyfobs from ebay and 2 blank blades. I had the blades cut to match my existing key and fitted these to the new keyfobs. I then used the normal method to pair both new keyfobs to my alarm/remote.
I was then left with the seemingly very expensive/difficult task of getting the new fobs paired to my immobiliser or getting my original transceiver code copied onto the new fobs. I spoke to a very pleasant but ultimately somewhat useless guy at my local Timpsons who informed me all they could do was provide a new basic key coded to my existing one “for £80 or so”. They would not under any circumstances touch my new fobs. This left me somewhat frustrated so I decided to see if I could obtain equipment that would allow me to copy the transceiver code onto the new keys myself. Unfortunately any equipment I found that may be able to do this was prohibitively expensive.
Next I toyed with the idea of programming new keys to the immobiliser and to my surprise I found this old post: https://www.rx8club.com/series-i-do-yourself-forum-73/diy-programming-new-key-when-you-only-have-one-forscan-262637/ this suggested doing such a thing was indeed not only possible but actually fairly easy. I purchased a BT OBDII reader, downloaded the latest version of FOREscan and registered with their forums (so I could apply for the required extended licence). Unfortunately I had issues connecting to my car correctly with this OBD reader so I ordered a different one, that claimed to be fully ELM327 compatible and tried again. The second OBD reader was even worse than the first so I returned it to Amazon. After a little more in-depth searching I found this OBD reader that claimed FOREScan compatibility: https://www.amazon.co.uk/gp/product/B06XPLSQRS
With this OBD reader I was indeed able to connect to my car and read all the diagnostic info correctly so I moved on to try programming my new keys into the immobiliser. Unfortunately once again I struck a problem, this time to do with having a keyless entry module, that prevents the software from programming keys. This issue seems to have been reported a few times now on the FOREScan forums but as yet is not resolved.
Interestingly the MX5 was reported to be compatible with PATS programming (used to add keys to the immobiliser) in FOREScan a couple of years ago. I therefore downloaded the version of FOREScan in which the MX5 NC was added in 2.3.4 beta, 2016-09-2. Using this version of the program I was able to access the key programming functionality successfully and added my 2 new keys to the immobiliser successfully. I now have 3 fully working remote keyfobs for my car that only cost me about £80 in total - result!
So if you’re in the position I was, worried about having only 1 key and the prohibitive cost of obtaining a second fob, fear not.
Hopefully this info will help some fellow Mazda owners 
Neil