I have a 98 S70, base model, 88K miles. I'm trying to start learning to do as much maintainence myself as I can. Anyway, the check engine light come on, and code for P0116. I know from the other posts that that is the code for Engine Coolant Temperature. I replaced the thermostat and ECT sensor, reset the CEL, but it came back on after about 50 miles. Temp guage always comes right to 3PM pretty quick, so I'm pretty sure the t-stat's not the problem. One thing was the replacement ECT Sensor was an 850 part. The parts store told me it should be the same part. Is that true, or could that have been the wrong sensor? If not the sensor, what else could be giving the code?

Another thing which has been happening the last couple days, which may or may not be related is its a little tougher to start (have to hold the key an extra second or two), and the engine fan comes on right away.

Also, I couldn't seem to find a consensus in other posts about whether the '98 S70 CEL will automatically reset after a few error-free trips.

Thanks very much for your help.