I just bought a used RX-8 and it only came with one key. I figured the remote for it has a dead battery so I replaced it with a fresh CR2025 battery. Turns out it still didn't work. I found some threads on here on how to do it,but it says you need about three keys to program it. Is there anyway I can do it with one key alone?

 

I had the same issue when I got my car. When you change the battery you have to reprogram the remote to your specific car. I followed this and it worked the first time for me.

Programming Instructions

Step 1: Open driver side door and leave open.

Step 2: Lock and Unlock the drivers door using the power door lock
switch on the door

Step 3: Insert key into the ignition.

Step 4: Turn Key to ON position and return to Lock (off) position. Do
this 3 times within 10 seconds. LEAVE key in the ignition in Lock (off)
position.

Step 5: Close and open the drivers door 3 times. Leave door open after
this step

Step 6: ECU should respond by locking and unlocking the doors once.

Step 7: Press any button on remote #1 twice. ECU responds by locking
and unlocking the car doors.

Step 8: Additional remotes, repeat Step 7 for up to 3 remotes total.

Step 9: Remove the key from the ignition and the ECU will respond a
final time with a series (about 4) of door locks and unlocks.

Read more: http://wiki.answers.com/Q/How_do_you...#ixzz1Dm7SWYS3

 

It work,but i think my remote is fried...it doesnt seem to respond I have a Visteon Model 41848