Hoping someone can help me or give me advice. My RS6 has been sitting in my driveway for the past year 'cause it won't pass emissions, possibly due to a few sensors (that I haven't had the money to replace) that recycle the exhaust until the engine warms up. Every month (give or take a week or two) I charge the battery, start it up, let it idle for about 5 minutes and then drive it around the neighborhood. Today when I started it, the radio read "Safe" and wouldn't play. My manual says nothing about "Safe". What's it mean and how do I fix it?

Also, does anyone know of a good hookup for a battery? It seems pretty specialized. So I'm guessing Audi charges $500-$1000 for one since that's what everything else on this car costs.

Thanks for your help!