While driving the low tire press warning came on after pulling into service station, approx 2 blocks pressure in tire was 25# when attempting to add air the valve stem end fell off exposing the shrader valve. after taking to dealer they replaced tire press monitor module under warranty. aapprox 6 months earlier i had a low air press warning on a different wheel and after driving about 1/4 mile home inspection showed valve stem was gone, dealer replaced press sender unit and tire at my expense. xc70 has tj24767 dated dec 2011 that addresses tpms nut corrosion. when dealer was question if this applied to xc60 was told they seldom see this problem but would not replace monitors. *tr