my friends Prius only has 1 key left, it drains the battery like within 1 day (using Duracells) what's the best way to fix this?
Partially depends if its a wireless smartkey or a traditional insertable key. Either way I would immediately go to a good locksmith (save a few dollars) or the dealer. When your key fails it is more expensive to replace and you are likely to need a tow. Having two is always smarter. If you lose the only one that works its the same more expensive situation.
My guess would be that one of the buttons is sticking in the 'on' position intermittently. I wouldn't waste any time getting a second fob, as RJ suggested above.
