O2 sensor won't budge

[VW NORTON]

I need to replace my 02 sensor on the cat but i can't loosen the old one.does anyone have any tips on how? It's in a tricky position and i am using the correct tool on the sensor but i am concerned about damaging the cat.

[ECS Tuning]

O2 sensors can be really tough to remove if they have been in the pipe a long time. You may try giving the edges a good tap to try and break loose the threads just a bit, then get the O2 sensor wrench on there. Once they break loose, they typically come out fairly easy.

[powershandyman]

I need to replace my 02 sensor on the cat but i can't loosen the old one.does anyone have any tips on how? It's in a tricky position and i am using the correct tool on the sensor but i am concerned about damaging the cat.

Have you tried undoing whilst the exhaust is hot? this sometimes heats up the nox boss and frees the sensor but be careful no to burn yourself