I purchased used Pilot. I am getting CHECK FUEL CAP message. I tightened the cap again but it did not go away. Then I got it cleared. Later on after the fill up the message came up again and now it is MIL (malfunctioning) icon on the dashboard. My mechanic has done his best but couldnot find anything. He is suggesting that may be we will have to change the sensor-is it worth it. This is fairly new car I should have to do this. Please help.