What size Tap for O2 sensors?

[94-302-vert]

I need to clean up the threads on my O/R H as the previous owner really jammed in the O2's (cross threaded too)... So I need to do something or I am stuck with the Catalytic convertor drone for a while...

 

[Yellow302]

assuming the O2 sensors all go in the same.

JEGS O2 Sensor Weld Fittings - JEGS

18mm threads

hope that helps, you can also look up the O2 sensor and see the thread type to match too.