trouble removing oxygen sensor

[SherA]

1992 Buick Regal
3.8L v6
Automatic
160K miles

Hi, after having failed CA emissions, I'm trying to replace the oxygen sensor and I'm having trouble removing the old one. I heard that the engine should be warmed up first to make it easier to remove it, so I did that. And I borrowed the removal tool from Auto Zone, but it is completely stuck and I'm afraid I might damage other components if I keep trying. Is it ok to use penetrating oil to try to get it loosened up enough so that I can get this thing off? Or is there a better way? Thanks for any help with this.

[BNaylor]

That is correct. Engine should be warmed up. Use any type of penetrating oil or WD40 where it mounts to the bung and let it set several hours or over night. It will not hurt anything. With the 02 sensor removal tool 7/8" socket turn counterclockwise and use a 1/2 drive ratchet with adapter since most universal 02 sockets are for 3/8" drive. Good luck and let us know how it turns out.

[SherA]

Thanks so much for your quick reply. I'll go and do that right now and then I'll give it another shot in the morning. I'll let you guys know how it goes. Thanks again!

[SherA]

Well, after I broke 2 tools working on it, I finally got it to come out. But it seems some metal was left in the threads so now I can't get the new one to go in. And I'm not sure what the thread size is supposed to be so I can fix it. What do I do in this situation? TIA

[BNaylor]

Bummer!

The 02 sensor bung at the exhaust pipe is a universal size. The bung size is 18mm diameter X 1.5mm pitch. You'll probably have to recut the damaged bung threads using the right size tap out of a metric tap and die set. Use cutters oil. Good luck!