Hi buddy the procedure is very simple but whether or not it will work is another story.
The last mitsubishi I tried doing a few month ago did work and I didn't even needed a
code to my surprise, but this pin codes are by region , a pin code for ausa model will
not work for europe as an example so one has to make sure the right region was
selected. Try it let me know how it worked out. Good luck

From control unit look for immo if is up to 2005, after that year it will say kos/immo/
wireless.

Remember to choose the correct region or it will not work. I don't have a mitsubishi at
this moment to tell you the rest of the procedure but it s very self explanatory once
your there. Good luck.

 the transponder read error could be many things from a bad key to receiver antenna , blown fuse or the ecu it self, its hard to tell without a full diagnostic. the first thing to do is to follow the trouble code procedure on the manual  to the teeth, also look at a wiring diagram for powers and grounds distribution  to all the modules involved, it should give you an idea on what you're dealing with. good luck let me know it went.

 If you find no wiring problems, you might try to jack up the voltage to the battery and use remote-head key, they send a stronger signal than common transponder key.