A few days ago I noticed one of my keys wouldn't lock/unlock my car or pop the trunk. I figured it needed a battery, so I replaced the batteries in both my keys. Now neither key will light up or do anything and if I lock the car with the key in the door and it sits more than a few days the alarm goes off. With both my boxster and my 996 I've had nothing but bad luck with keys/alarm/central locking. I really don't want to go to the dealership. Any ideas?

 

If you're not getting any light on the key you might want to check that the battery polarity is correct or even if the battery is good. Seems like the easiest first step in troubleshooting.

 

Please note from the owners manual - if the car is locked and the alarm is active, the immobilizer in the car puts the car to sleep after 4-5 days where it shuts down the immobilizer to conserve the battery. It simply stops listening for a key signal and the car must be unlocked manually.

 

my windshield sunshade fell down so I think that may have set off the alarm? ive been through 4 different batteries making sure they were installed correctly but no go, I think the circuit boards in the key heads are done, I will bite the bullet and go to the dealer and get at least 1 new key made

 

I had the same problem with both of my keys. I tried the "trick" of holding down the lock button for six seconds after manually unlocking the door to "resync" the key with the car. No dice. I ended up taking it to Porsche out here in Santa Clara and was told that those 996 keys have circuit boards that go bad after about 10 years. Sometimes the light will still turn on when you press the buttons, but the car will never respond no matter what you do.

The temporary solution was to remember that you turn left to unlock, turn right to lock when you are manually opening the door. If you do the reverse the alarm will go off. When you get the door open you have to start the car within 10 seconds or the alarm will go off. This is because the car needs to "read" the key when it is unlocked manually or it assumes it was jacked.

Porsche charged me about $330 per key for parts and labor to get me a new set.