My exhaust fell off at the flex pipe and it’s dragging on the ground and I was going to see if I could just remove it and straight pipe it but the o2 sensor on the cat is stopping me from doing so I’m just wondering if I can remove the o2 sensor and will it run normal?

 

No the oz sensors tell the ECM how much air and fuel to fire so the engine can run efficiently. A new pipe from the manifold to the flange isn’t that much, five fasteners and those 2 sensors.

I’ve installed these in several HHRs
I see yours is a 2008

https://mufflerexpress.ca/products/c...-2-2l-and-2-4l

 

If the whole system did not get trashed all you need is a new flex pipe.