new owner asc question

Hi all I am the proud new owner of a'95 540i and was just curious if anyone is familiar with the asc system.Here's the short version 'I was told that one of the speed sensors was faulty and requires the car to be in asc mode{button on ,Symbol lit up} or it won't take her power right and it's true,without the system engaged it makes rear noise and acts like my old audi quattro did if you left it locked in on dry pavement!Withe system engaged she drives perfectly,lots of
power rides beautiful.: