2004 Mazda 3: Remote Key Malfunctioning


I have a 2004 Mazda 3s with 210k miles. Both the remote key’s just stopped working. The dealership tried replaced batteries and tried reprogramming the key’s but said that the computer is not accepting the keys (these are original keys). They suggested replacing the computer but in my opinion the car is not worth that much …

I tested the remotes at autozone and they seem to transmit rf signals. The door locks or control modules work fine - the problem appears to be the remotes or the communication between ecu & remotes. Any suggestions or advice?

Thanks in advance.

Have you tried reprogramming the keys yourself? Won’t cost you anything to try…

As I see it, you could:

-Shell out the money for a new ‘computer’ – probably a BCM or “body controller module” It may be that the RF section that receives the radio signal is a separate module that can be replaced, but probably not.
-See if you can get a used or remanufactured one a lot cheaper. Best to check if a used one can be reprogrammed–some are finicky when it comes to vehicle security.
-Use the mechanical key to unlock your car until you get rid of it.
-See if you can adapt an aftermarket unit to actuate your locks.

I doubt reprogramming them yourself will work if the dealer has tried with their scan tool. Normally you’d need 2 keys to reprogram a 3rd, 4th, etc. Since your 2 are apparently not recognized, I don’t think this will help.

Thank you for the replies!

Reprogramming did not work. I am using the key manually… will probably be on the look out for a used computer.