Q&A

 Rookie

When I start the car it idles just fine. but after I get up to speed and then stop at a stop light or anywhere it idles high. anywhere from 1300-2400 rpm. it doesn't seem to matter how fast I have been going of how long I have been driving. also the check engine light comes on sometimes... but not often. I had it hooked up to a computer and it says egr valve fault and knock sensor. any ideas which one of those it is if either?