Arno,

Thanks for the advice. Following along the same lines, this past winter I was getting very little, if any, heat in the passenger compartment. Other symptoms: my radiator fan would continue running a minute or so after I shut the engine off in cold and hot weather, and my temperature gauge would not move at all until I had driven the car for 2-3 miles, and then only up to the 5 o'clock position (it would never get to the 3 o'clock position). I suspected it was a faulty thermostat that was stuck open. I understand that this can prevent the engine from reaching its optimal operating temperature and cause the ECU to add fuel, thus run rich, thus high HC content, thus fail emissions test. So I pulled out the old thermostat today and, sure enough, it was stuck open. I dropped a new thermostat in and took it for a test ride. The temperature gauge now moves up immediately when I turn the car on, but only to about the 4 o'clock position, still not the midpoint. I'm going to try passing the emissions test tomorrow. If I fail, I'll drop a new temperature sensor in. In fact, even if I pass I'll have it checked out to make sure my engine is running properly. I'll update you when the results are in.