Is it possible if car battery is low on power it can cause fob not found to illuminate and prevent ignition display not appearing Fob been tested and battery replaced but sometimes getting fob not found come up Think battery on car is older than 5 years old and wondered if it was failing to open circuit for ignition and giving fob not found reading Starting become worse since wet weather and having to run lights heater and wipers even though it gets good mileage runs

 

Sounds like this is a x250 not x260? If the Battery is 5 years old it's after the redesign of 2016 putting it in the X250 segment. I'm not sure many x260's will have had experience with a dying battery due to age yet on this section of the forums; I would try the Modern section and see if anyone has any insight. I'm too new of a XF owner to have much opinion unfortunately, While it could be the battery, and not the alternator (since obviously your car can run after starting) I would take it to a car parts store and have them put a battery tester on it. Most car parts stores do this for free, in the US anyways.

I would think though that if your battery was failing you would have some starting issues as well as most car functions use much less power to operate than the strain of starting the engine. This is where my experience with these cars shows, because I don't know if they have systems in place that rely on specific voltages to remain fully operable. I wouldn't be surprised if the system has voltage requirements to both protect the sensitive components but also to prolong the usability of the car during battery failure.