I'm somewhat irritated with my '95 C280. This is the third time in less than a year that my CE light has come on.

In the past year I've had my wiring harness, throttle, blinker switch, and a fan replaced. My oil and coolant have been filled, and I had a tune-up done a few months ago.

Just yesterday, I took her in to be smogged. She has been running wonderfully, so I knew she would pass.
Upon leaving the smog facility, I noticed my engine temp was about 100 on the gauge. I drove roughly 30 miles, and during my drive, the temperature returned to 'normal' so I didn't think much about it.
When driving home from work (Another 30 miles), I noticed the CE light come on. "F--- what now?!"

When I arrived at school, everything under the hood looked great. When I checked my gas cap, the darn thing was not tightened all the way. I fixed that, but the CE light is still on.

I reviewed my smog paperwork and the levels looked fine, except for the HC (PPM). These levels were spot-on the MAX range. I'm wondering if the loose gas cap maybe affected the results, and why my temp was so high. The car runs just great, and I do not hear any noises.

Unfortunately I do not have access to a code reader right now, but I was wondering if anyone could speculate, or offer suggestions as what to do in the meantime.

Thanks!