Keyless Entry/Start System Slowly Failing

Hi there, I have a 2004 Prius that I have had no problems with until now.

Over the past two weeks my keyless entry and start system has been failing to recognize my "key". First I couldn't unlock and open the hatchback, then the system wasn't opening the driver's side door. Now, I have to use my traditional key to open my door and then plug my "key" into its slot to start the car (hence, the system isn't recognizing I am sitting in the car and trying to start it).

Is this a fuse issue, or a programming one? I had heard reprogramming the keyless system is expensive, especially when needing to order new keys. Fortunately, I have a 5 year warranty, which I believe should cover the above mentioned glitch. Any advice out there? Thank you in advance!

Alex-

 

nevermind..I realized my fob battery is dead, and will replace it. Thanks Priuschat!

 

Yea, I bought the car new back in 2004. It seems from my own experience, as well as from the other posts I read, the battery life of the fobs (when being used for the keyless entry/start) is around 4-5 years. Also, some good advice I read: when the battery life is dwindling, the car will make a single beep after you power it off. I was really beginning to wonder what the sound was, but now it all makes sense. Will know better in the future.