I'm looking for the exact thread specifications for the O2 sensor for a 1999 lexus rx300 that threads into the bank 2 exhaust manifold. I took out the old O2 sensor and cannot thread in the new sensor because the treads in the exhaust manifold are slightly damaged and need to be cleaned up with the proper tap. I'm pretty sure that the tread is 18mm and more than likely 1.50 pitch, but I was wondering if anybody know the tread specs and can confirm size and pitch specs for me. I need to track down the proper tap, but want to make sure that I'm using the right one.

 

Jimfab- If you want an easy way to deal with it- follow me. Are the threads messed up on your old sensor also? (As in did it gall both the sensor and the female threads?) If the old sensor threads aren't bad, if you have access to air and a die grinder and a cut-off blade, simply cut about 4 grooves equally spaced around the beginning of the threads. It should look very much like a tap although I don't cut them as far up or as wide as tap grooves. Grease it with a light grease or oil. It will work just like a tap! You have to remember that the manifold that the threads are in is stainless so that galls easy. Work it just like a tap, back and forth and a little farther each time. That has gotten me out of the mud more times than I can even remember when working on Japanese cars because they have such soft bolts and fine threads that they gall and get messed up just breathing on them. LOL Try it, it really does work! If you don't have the equipment I mentioned , use a bench grinder to put the grooves in the old sensor or worst case scenerio, a hack saw. Good Luck!

 

Excellent, something I too have done. learned it from my dad an old air craft mechanic...
great tip code58