Got AUDI A4 - 2 years old now. Car was telling me to replace battery - I did (twice)...same problem. So I used my spare FOB. Was fine for a while then same message appeared for 2nd key. Went into AUDI spares - they sold me 2 batteries and fitted them. I returned to the car and the message had gone (but got 2 fobs inside the car). I find now that one of the keys is telling me, you guessed it - 'replace battery'. Incidentally the original faulty fob worked OK for a while when I encountered the problem with the 2nd fob. So one day you are fine, the next day you are not.
That’s really odd. I know batteries don’t last that long in the fob but new batteries should fix the issue. No accidental pressing while the fobs are on the go with you. Like left in bottom of gym bags etc. the mrs handbag.
My RS6 did this the other week, 'change key battery'' on the dash. My dealer who supplied the car did it for free & as soon as i got back to the car the message went & all is fine.
