I bought a 370z... but it didn't come with the right key.

ChaseZ

Skipped past most of the responses so perhaps this was covered, but the reason you've not had any issue with the programming working is the second hand transmitter that was obviously programmed for the car somewhere along the lines works just fine. If it wasn't going to work it wouldn't have worked all along. Why after 2.5 years could you be having an issue? There is one answer.

The battery.

Replace the battery in the key fob and I bet it works just fine again. All you need from Nissan is the physical key insert ordered and then cut to match your tumblers.


And yes Mitsubishi dealer should cover the physical key replacement, or the entire fob if that's how it has to be ordered by vin.