how many items can stop the computer from going in to closed loop?? i have an o2 sensor bad at the moment is it really that picky?!

 

I had a bad Heated O2 sensor and mine wouldn't go into closed loop!

 

Here's a link to Injuneer's site explaining closed loop and much more:

http://members.aol.com/InjuneerZZ/ScanMast.htm

The short answer is:
-The O2 sensors have reached operating temperature and are beginning to cycle above and below 450mV

-The coolant temperature has reached the minimum set in the PCM. This seems to be in the range of 120 -140 degrees F.

-The "timer" has timed out - this seems to vary from 3 to 5 minutes, and seems to be longer in colder weather.