STC Button

Hi, you are right that the yellow warning light will flash on when then vehicle is slipping, but should go out again when full traction is regained. The STC (Stability Traction Control) also known as Dynamic Stability & Traction Control on older model S80's (both options were available). The STC on older s80's had a button on the dash to disengage it. On the current model with the 'Floating Centre Console' in Volvo speak is much tidier, and this function has been moved into one the many options available on the centre display (dependant on model). Scan through to vehicle (car) functions & you will be able to disengage it should you wish. On some other current Volvo's this option is found via the 'Read' & trip computer options. It maybe found there on your S80 as functions have been moved around dependant on Model Year etc. Hope this answers your question?

you need to change the reluctor ring, 80 quid, simple job