Drove my 2011 xkr Convertible to and in the Veterans Parade on the 11th, returned home to the garage, no problem. Plugged in my Battery Tender. Went to the garage this morning to reposition on my lift and when tried to start, "KEY NOT FOUND"
So looked for my other key fob and I can't find !! Put the one I had in the globe box and car starts. Checked battery in FOB ok but replaced it with new anyway. Still not found. Was thinking that I've had the car 6 years and never changed the car
battery. Might that have an impact on key not found ??? So I'll put the top up and check the status of the battery !!! Could this be the culprit ??

 

That's 1 way of finding out that you need to replace the battery.It starts throwing problem codes that's not giving you problems at all.I sort of replace my battery around every 3 to 5 years