Key Transponder not Working
 

My key transponder hss stopped working. I've put in a new battery so its not that.
Car is a 2003 Boxster w/ 96.000 mi.
Any ideas?

Try using it manually in the door, I read somewhere that it can reset this way but I never had to try it. Otherwise, I would think only a dealer reprogramming will do.

Welcome. There are several things that can be wrong. Search for key fob as there are many, many threads about this. Can be guts worn out, programming, or power failure (even with a new battery). Have your dealership test it and reprogram if it's working per specs.

The trick that worked for me was to open it up, put the battery in with reverse polarity for 30 seconds or so, then flip it back. Worked like a charm. Strange but true.

Ordered a new KEY FOB off of Ebay and replaced my broken key head and its working great. Paid $39 for the 2 button key head (no electronics).

Wow, had an intermittent fob issue, new switches, battery etc, seemed fine then just stopped working!
Tried Jakekit's battery reversal and it worked!

While this is fantastic news, how does this work, does it reset the chip in the key?

Theres 4 main pairts to the transponder mess,

1) A coded "pill in the key fob
2) and inductive transceiver around the key slot connected to a
3) Mystery box connected to
4) Immobilizer box under seat which sends an A.O.K. signal to
5) the DME

Most likely prob. in my experiences is immobilizer box under the seat gets soaked. Take it out, dry it out, clean it good and you may be O.K.. BUT FIND THE LEAK.
Regards, pk