Check engine light is driving me crazy

I have a 2000 Cadillac Catara that has just had an o2 sensor replaced. When I picked the car up after the repair the outside temp was in the 40’s. After the car was parked for 4-5 hours and the outside temp was around 31 degrees I drove less than a mile and the light came back on. It seems when it’s a warmish day here in upstate NY the light is off but as soon as it gets cold there it is! Any ideas? It’s been in the shop 3 times in the last 3 weeks. I just bought the car in Feb so I don’t know it’s history.

Yup, I have an idea. My idea is that your car is misfiring when cold due to improper fuel metering due to some sensor being defective, perhaps the temp sensor.

But in truth I’m guessing wildly. Many parts stores will read the fault codes from the ECU for free. Have them read and post them here. We’ll try to help based on what they indicate.

Get the code read at an auto parts store, like Auto Zone, Advance, etc., free. Bring those codes here in their raw form, such as P0140, Pxxx. We can then guide you to peace and happiness, or, at least, to Xanadu.

Brilliant! I will take the car to the closest auto parts store today and let you know. Thank you so much! I knew someone would have an idea…

I’m taking the car to the closest auto parts store today and I will get the codes to you. Thank you so much! Peace and happiness sounds wonderful—and an extra large bottle of hair dye might do the trick to get rid of the new gray hairs that have sprung up overnight over this!!! Have a great day!!!

On some vehicles there is a reset switch near the filter area and I believe this can be pushed to stop the problem. If the code reads change filter, then this is a posibility, worked on my '02 Ford Explorer. I am not familiar with your car, but maybe someone can elaborate.