Removing a stuck NOX outlet sensor

You could have the truck at operating temperature and then try a sensor socket with a long breaker bar or ratchet.
When cold spray blaster on there several times over several hours and let sit overnight.
Heat the area with a torch.
FYI on this tool. I don't see the components sold individually.
Milton Industries LT996D Milton Shockit Socket Sensor Removal Kits | Summit Racing

Sometimes the bung (what the sensor screws into) needs to be replaced.

 

I'll sometimes cut the sensor lead off and use a regular 6pt socket. Then heat it up a bit.

 

You’re going to need some heat. If you can get it in a regen it would help. If not you can use a map gas torch.
Sometimes you can tighten it to break it free.

 

Heat around the sensor,not the sensor itself.

 

P b blaster and acetone

 

I use kroil for nuts and bolts that don’t want to move.

 

Nuts Off works really well for hard stuck nuts. I used to use that stuff out in the oilfield and it worked like no other.