I had metal valve caps on mine too. Damn thing rusted on one. When I tried to twist it off with a pliers I broke the stem. Had to have it replaced at the dealer and they couldn't reset the light either because they didn't have the tool to do it. Had to take the car over to another Chrysler dealer and have them do it. But I don't understand why the dealer wants the OP to replace all four sensors. They should only replace the bad one. The part was about $78.00 and with labor it came out to a little over $160.