My son borrowed my car, 1998 E300DT, for a trip to Washington DC last night, and called me while on the Jersey TPK with a problem. The check engine light came on, and also a notice to check engine electronics. The car has 48K, and no lights ever came on before. He had just filled up with, I hope, good Diesel fuel...He was sure it was diesel.(I hope it wasn't gasoline by accident as he has a C280 and is used to saying fill it up). The light came on about 15 minutes after the fill up. I called Roadside assistance, and they felt it was a minor problem probably related to some pollution control problem. The light stays on even pushing the reset button. My son felt that the car was stuck in one gear, probably 3rd or 4th for about 15 minutes, then after he said it felt like it was changing gears allright. He is in Washington now and I don't know what to tell him. The car seems to be working OK even with the warning lights on. Any thoughts about taking the 4 hour drive back to NJ with the warning light on? I don't want him to get stuck in a strange dealership so far from home. Any thoughts about the cause? No fluids were spilled on the controls. Anything he could check under the hood for a simple cause and cure? Thank you for any advice. RSL007