No, but incorrect fueling can fuck a cat if you have one.

I've told you the answer, your car does not have to run closed loop control at idle, so if you want to make sure the lambda stategy still works correctly, monitor the fueling at cruise which should be lambda 1.

I'd expect your idle Co to be around 1 - 1.5% CO, though up to 3.5% is MOT passable.