Key fob issues

Yesterday afternoon I was unable to unlock my Prius with the key fob. It had been working fine all day, no low key battery warnings or anything. I tried installing a new battery and everything started working.

This morning the fob stopped working again. On a whim I pulled out my multimeter to test the batteries. The new one read 1.5 while the one I thought to be bad read 2.9. So I switched back to the old battery and the fob works again.

Has anyone encountered this sort of weirdness before?

I'm going to check with the dealer next week. My first thoughts are that either the new battery is defective or something in the fob is draining the batteries prematurely. But none of that explains why I couldn't unlock or start the car normally yesterday.

I guess I still have the valet key as a backup. Worst case, can I keep driving with the 'key not detected' message showing? Thanks.

 

Thanks for the response. I think I have it narrowed down to a faulty fob. I checked six hours later and found it had stopped working again.

I tried putting a good battery in my second fob. So far so good.

I hope I can get a replacement under the warranty?

 

In case anyone else encounters this...

The dealer tested the fob with a new battery, determined it was functioning, then charged me $6 for the battery. 30 minutes later it stopped working again. It's covered by the basic warranty so I'll be getting a new one later this week.