Deactivating the lost key.

[vicky]

Sometime back, I bought a used Yaris 2010 sedan which came with 2 keys (with remote lock).

It looks like, I've lost one of the keys. I'm currently using the other key. However I'm worried about the lost key falling into the wrong hands.

When I asked my dealer about deactivating the other key, I was told that I have to replace the entire set (keys + car receiver) which will cost thousands.

I'm fine with one key for now. Is it possible at all to just deactivate the other key? Or if I have to replace the whole set, as the dealer told me, what would be the way to go about it without costing me thousands?

Any advice on what I can do at this point would be greatly appreciated. I tried searching on the forums but couldn't locate a direct answer.