ok everyone i got some problems.......... i have a 2000 cavalier 2.2 2200 ohv the cooling fan turns on automatically when my car turns on and my check engine light is on......... got the code checked and it said i had a bad temperature sensor, weak O2 sensor (the one after the cat), and here is something really strange... my IAT is measuring that its negative 40 degrees outside??? wat the hell is wrong wit my car??? i jus replaced the IAT cuz i lost the other one when putting in my Cold air intake....... any help would be greatly appreciated thanks

i not to positive on a j but on my trans am when my supercharger belt broke the conlant sensor for the gauge my fan ran all the time. Now i figure on the cav sense it is saying its bad in returns keeping the fan on. So it won't over heat maybe.

Now on the sensor after the cat reading low. Your cat might be stopped up. But that sensor doesn't affect the cars performance any. But i would have the cat checked out.

Maybe the sensor was bad you baught. Take it back and get another one and see if it still does it. Also if you extended the wires for the intake the wires might have a bad connection to each other somewhere

also this should probably be in the maintenance forum.