need a little help..

my 2000 a6, non-turbo, non-quattro, makes a warbling sound when I turn. seems to come from left front wheel area. tires are good, rotors seem good(what do i know?) any ideas?

also, my brake light flashes and ABS light stays illuminated after every engine start. is this an ABS controller needing replacement? is my anti-lock brake system still working?

thanks for the help

 

SOUNDS LIKE A BRAKE SENSORS ON THERE WAY OUT.