Hi guys:

I'm trying to get my sister's c-280 smog-certified so the registration can be renewed again. When i took it to a smog test center, they did a pretest and the smog emissions passed, but the check engine light failed to go off after the car started. He suggested that i send it to the dealer to have it repaired before getting a test only center to run the test again. He also mentioned that i should replace the gas cap. Although i'm not quite sure how that'll help in improving this car's smog emissions, but i guess i'll have to give it a shot.

P.S. does anyone know what an EGR is and what it does? Is it hard to replace? Expensive?

TIA!

Mars