Our 2000 C280 had the B service performed by Ewing ******** in Plano, Texas 4 months ago @ 35,190 miles. The Check Engine light came on about three weeks ago @ about 37,000 miles and we took it back to Ewing. They checked it out and said the only thing they could find was a loose gas cap. The mechanic said to fill the tank again and drive it for a while and the light should go out - if not we were to take it back to them. After two fill ups the light is still on. Any ideas? Also, can anyone recommend a good shop in/around Collin County, Texas? Thanks in advance!