Yaw rate sensor problem_ESP light flashing
 

Hi, I have an Audi Quatro, A6, 2003. The ESP light keeps flashing despite turning the engine off and on. Last week it suddenly had all 4 wheels jammed while driving at 50km/hr. Got the brake pads and sensors as well as the front drive shafts replaced. The ESP light (Exclamation mark with a triangle around it and a circular arrow over it) still keep flashing and every now and then the front right wheel makes a grunting noise for a second or so. My mechanic says Yaw Rate sensor, the little BOSCH cube, under the rear seats, needs to be replaced. He mentioned it would cost 2.5K AUD !!!

Anyone who know whats the deal with Yaw rate sensor ? could I just turn off ESP and keep driving ? can I buy this Yaw rate sensor off eBay or something ? Any other options I have ?

Cheers.