Pontiac Repair: 01 Aztek problem. Cooling or Electrical?, electric cooling fan, auto parts stores

Question
I have an '01 Aztek GT that is behaving strangely.

From time to time the Check Engine/Service Vehicle Soon lights will come on.  When they do, I've noticed a few things:
-  The engine temp gauge will stop registering completely.  The needle will fall to the same position as when the engine is off/key out of the ignition.
-  The external temperature display in the dash will start to increase when I stop at a traffic light.  It will increase 4-5 degrees in the span of a single red light.  Once I start moving, it will go down again.
-  Once I shut off the engine, the electric cooling fan will continue to run for a few minutes.

This never seems to last very long, a day at most, and then it will 'reset' itself.  The service light will go off and the temp gauge will behave normally.  I've also noticed that when it does reset itself, the engine temp does not appear to be any hotter than it should be.

This car has a lonnngg history of electrical problems.  Could this is another one, or does this seem more like a cooling system problem?

Thanks for your time.

-mas

Answer
Hi there:

well first off I would have the car scanned for codes and see what codes are stored in what modules and go from there. The temp gauge and the service engine soon lamp may be related. The engine telp sensor controls fuel injection in part and it also controls the guage on the dash. If ther is an issue with the ckts' to the sensor or the sensor it's self in can cause the lamp on  the guages issue and the fans to run. As for the rest of the issues You may have an issue with the ambient temp sensor for the DIC. Different sensor then the engine temp sensor. Again I would get the car scanned for codes any of the big box auto parts stores will do it for free. good luck :-}