i took it to a volvo specialist, not the dealer. dealers are bandits.

i suggested several times that the sensor itself may be faulty, but the tech insisted that the diagnostic would have found the sensor failure. it is possible that he was too lazy to delve further into the problem, but judging by the number of volvos in his lot (at any given time), i would think he knows what he's doing.

thanks for the opinion, though.

-andrew