lately my truck's check engine light comes on when im putting down the freeway. comes on almost everytime i make my 20mile commute home. sometime it goes out after a couple minutes, sometimes stays on til i shut it off. light stays off if i restart. its always a code 32(faulty EGR) i had the EGR replaced about a year ago. i used to get a code 32 when putting around at high altitude.but only in the mountains, never at sea level. could the EGR valve gone bad already? or is there something else to look for. it was replaced at the dealer so im pretty sure it was a quality part. whats the service life of a EGR valve? are they supposed to be replaced every 15k like sparkplugs?