I drive a 2006 s40 and am experiencing problems with my key fob. Ive owned it for 2 years now and love it, however my fob had been getting weaker and weaker. I opened the key fob to see the battery type and put it back together but it didn't work the next day (thought maybe the battery finally putzed out) when I tried to press the keys on the fob. I then used my valet key to unlock my driver side (my only option) and my alarm went off. It stopped after I inserted the fob into the ignition, and my car starts just fine with the fob. That's the only function it seems to recognize is to start the car. I've tried all the tricks to reprogram the key fob with no avail. I changed the battery out with a new one and that didn't help either. I'm trying to avoid a dealership visit...any suggestions or experiences and best practices would be greatly appreciated. Thanks!!!

 

Have you checked to ensure that the button battery in the key fob is inserted the correct way round and is equivalent type to its predecessor?