1997 Carrera Targa. The remote fob unlocks the car and disables the immobilizer so tha car can start, but when I park the car and lock it using the key fob it locks but after a while the hazard lights start flashing. This seems to have started after the battery drained completely and was replaced.

SOURCE: 1997 Porsche Carrera S ---

Hi,

Maybe you can try this procedure to resyn your key.
Initialization Procedure.

1. Open central locking system using the car key.
2. Get into the car and close all doors.
3. Using the car key, switch the ignition lock briefly to position "1" and then switch off again. (Please do this switching within 5 seconds or otherwise the system is not ready for initialization.
4. At the remote control key. Press the "OPEN" key (->) and keep holding.
5. When holding the "OPEN" key, press the "LOCK" button three time.
6. After pressing the "LOCK" button 3 times, release the "OPEN" button.
7. If the initialization process is sucessful, the door will lock and unlock immediately to confirm the process.

SOURCE: how to disable honda accord 1997 Immobilizer

I show immobilizers where only started in the 1998 accords, if you have a remote starter and they used a key in the box bypass all you need to do is find the box under the dash open it up and use the key

SOURCE: I have a 1997 ford explorer and the remote fob

I believe you have to take it to a dealer.

SOURCE: Porsche 2000 911 Carrera. Key fob problem

each vehicle is different put the key in the ign. turn key on press door lock/unlock at the same timehold button for 10 sec see if any lights on the dash inst. panel blink if they do that means that the key fob was programmed to your vehicle i recommend a new key fob this will give you definative instructions on how to reprogram your fob

SOURCE: Lost alarm key fob - trying to change drained

try locking and unlocking drivers door lock with the key