Tricky Question for the Gurus

[yakko]

This is more of a 'why' than a 'how' question...

I have a 2002 Regal LS and I've neglected my cooling system for awhile. I know, I know, I'm a bad person. I have had a service engine soon light on for awhile which when I took it to the parts store, they hooked up and told me my thermostat was stuck open.
Well I'm going on a trip for Christmas and wanted to finally get that thermostat taken care of and do a quick flush while I'm at it. After all was said and done, I still had a SES light on. I took it to the Zone and they said I had a cooling sensor fault and an O² sensor fault (P1133).
Now I had given the engine plenty of time to heat up, but an hour or so later when I drove on the highway and got up some speed, the SES light went out and has not come back on.
Now I can understand the cooling sensor may of had some gunk on it and that a flush took care of that, but my question is... could that have affected the O² sensor by somehow causing the engine to run cooler than it should of for this long or something like that? I guess it could make sense, but does anyone have a 'professional' answer?
Thanks.

[BNaylor]

Not clear by your post but did you replace the thermostat?

The engine coolant temperature sensor (ECT) could affect when the PCM module switches to closed loop mode from open loop mode after proper engine warmup. The 02 sensor input is used in closed loop mode only. Note: The same ECT sensor is used to provide the engine temperature reading to the temperature gauge at the IP Cluster so is that reading proper? Should be around 195 degrees after sufficient engine warmup and weather conditions.

I didn't see it posted but what is the code for the cooling sensor fault?

One of the enabling parameters to set the P1133 DTC is coolant temperature being closer to normal or greater than 50 degrees C or 122 degrees F so it may not be related to the reason why you are getting the 02 sensor DTC. The P1133 DTC means you have a lazy bank 1, sensor 1 02 sensor or slow to respond.

[yakko]

I did replace the thermostat and flushed the coolant.

I didn't get the actual code for the coolant system. The $#@ at autozone wouldn't give it to me. While he was getting the codes, I asked my girlfriend to see if she could find a pen and paper in the passenger seat. She got in, found the pad and pen and decided she would write down what needed to be written down while I was on the outside of the car. I asked him to tell her the codes and he mumbled some stuff to her which I thought were the codes, but on the way home I found out he told her, cooling sensor, O² sensor, and P1133. I even called the autozone back to try and get the other two codes but they couldn't help me at that point. I was angry.

Thanks for the reply. The SES light is still not on so I think it is good to go. It just bothers me when I don't know the 'why'.