2018 Model S Old and New Key Fobs Compatible With Each Other

[obie_fl]

Did a search but came up empty.

I lost one of my original key fobs from my early 2018 MS and wanted to get a replacement second fob. The tech came out today and programed a new fob and it worked, but then my old one stopped working. He then reprogrammed the original fob and the new one quit working. I suspect the newer (80 bit?) fobs are not compatible with the original (40 bit). I asked him to program two new ones but I'm not sure he did. He rescheduled another appointment.

Does anyone know if you can have new and old fobs programed to the car at the same time?

 

[PCMc]

I've always heard that for the earlier vintage MS that when programming a fob that you must have all your fobs reprogrammed at the same time. It sounds like he was only programming one of them, expecting the other to still work, versus reprogramming the car to recognize both fobs at the same time.

Could be that he's just poorly informed on this since the new MS the programming of the fobs is pretty easy and he realize this complication on the older versions?