I bought a 2001 RX300 and it had 1 key with remote. The remote was malfunctioning so I bought an extra key from Ebay. I changed the transponder from the extra remote into the old remote and was able to program the remote successfully. However, now the key won't start the car. Do I need to reprogram the key as well. If so, how

 

When you say that u were able to program the key successfully, do u mean by: Successfully able to progrram it to unlock the doors with the remote or successfully able to start the car? If you were able to successfully program it to start the car in the past and now it doesnt' work. Maybe you should try changing the battery.

 

what i mean is that the key I had was able to start the car. After I bought a used remote and programmed the keyless entry the key will not start the car anymore. While I was programing the remote, could I have erased the code to start the engine?

 

You need to reprogram the key, You might of have erase it. go to this link and the instructions are there.

https://www.clublexus.com/forums/sho...threadid=72242

 

The problem is that I have 1 master, 1 valet, and 1 keycard.