i have a 99 venture, v6, O2 sensor went bad up by motor (not the one by cat) got new one, finnaly got old one out but new one wont thread in, new one is exactly like old one, smae threads and size, any ideas on why it wont thread in? acts like threads just wont start. maybe run motor some a heat up manifold to expand metal to make it work?

 

Clean/retap threads

 

you happen to know what size tap it takes? done some searching but no luck and guy at napa had no idea

 

Keep trying, looks like a 18mm. Take the sensor with you to match threads.

 

update!!!!!!! for everyone else with this problem here is what i had to do.. found out the 02 sensors are the same as a sparkplug, 18mm... went to autozone and bought a sparkplug thread chaser (i got the one that has 18mm and 14mm ends like $7) , i had to ground a bevel on the chaser to get it to start threading in, forward-reverse-forward-reverse kept doing that until it went in all the way an cleaned the threads on the manifold. new 02 sensor screwed right in!!!!!!! by the way this is like a one handed job going up from under the motor right beside the exhaust pipe. good luck to anyone else needing to tackle this job...