Oxygen Sensor not Budging
 

The oxygen sensor on my car will not come out. Maybe rusted in? I've downed it in WD40, but it still won't break loose. Any ideas?

WD-40 is useless in this application. Get a proper penetrating oil such as Liquid Wrench or Kroil. Try several applications, waiting a half-hour or so each time to give it time to work. If it still won't budge, heat the bung red-hot with a propane torch to loosen its grip. You may still need to whack the wrench handle with a sledgehammer to break it free.

Or just let the car run for about 15min. It'll heat up enough normally to help crack it free.

That looks pretty thorough, thank you sir, I'll give that a try. Will liquid wrench still be effective in temperatures close to 0 degrees Fahrenheit? I live in Utah and the weather has been brutal lately.

But if I do that then the pipes will also be hot. Then it's difficult to wrench it off without burning the hand/arm.

Whether you run the engine or use a torch, you run the risk of burns--you should be wearing long sleeves (cotton or wool, no synthetics--they melt!) and mechanics' gloves for this job if you're even the least bit clumsy. Helps avoid the near-inevitable bloodshed when it finally lets go, too. ;)

Most penetrants will not work well in deep cold. Use the torch or the engine to warm the assembly before each application.

A company I sell through my work (KOI Autoparts) "Roadmaster" sells a kevlar heat sleeve. Part number KVBK18TS-T .. you can google it if you don't know what it is. But it basically allows you to accidently hit the hot pipe and not burn yourself because it will happen lol. We sell them for 20.99 for walk in customers so Im sure it could be found cheaper.

unplug and drive. mpgs may suffer a lil but you dont have to worry about burning yourself

Stud removal
 

Women are attracted to us mechanics, because of our scars :yikes:
I believe in safety first, so if you do not feel comfortable doing a job leave it :thumbup:
I always wear slip slops & I had a melting piece of steel fall between toes & burn itself into the flesh, where I had to rip it out forcefully :wailing: The infection afterward was caused by me jumping into the nearest pan of fluid availiable to ease the pain- it was a old Antifreeze concoction :flame:
I have also burnt myself, by barefootedly stepping into a BBQ coal that had fallen out of my 44 Gallon drum BBQ :drink:
Recently my Cousin stepped barefoot onto a yellow scorpion. It only hurt when the Alcohol wore off :doh:
But the above only hurts a short time, whilst Safety boots are always a pain- Your choice :dunno:

But to get back on topic:
These sensors seize, like exhaust studs, because people do not apply a thin coat of Coppa slip on the thread during assembly :banghead:
It is easy ! Spray penetrating oil onto the offending fastener when hot (keep away face) and then let it penetrate through the engine cooling off. You should even be able to undo said fastener without needing to heat engine up again :bustingup

Boy it's a real bugger. I heated it up through running it, torched it, liquid wrench, pipe on the end of the wrench, nearly everything. I'm beginning to deform the bolt, and yet it still doesn't budge. Not sure where to go from here.

And sorry about your foot man, that sounded pretty brutal.

On ya Nick!! Back to the plot - Use the correct socket or a good ring spanner. Work on it cold. Try to TIGHTEN IT SLIGHTLY first and then remove. I'm amazed the pipe has not torn open with the force you say you are using. If possible soak with your favourite penitrant over night (cold) before having another go.

my idea is starting to become a prime choice........

or if you are very careful and good aim, hit the o2 sensor with a hammer. the best way it to hit it from the top (yeah i know virtually impossible while exhaust is mounted on the car) but, that leads me to the next part, remove the exhaust then try

Well the trick was getting the car up on a lift. That gave me a better angle and it was easier to put all my weight into it. We heated the bung to red hot and started torquing it off. The threads were pretty shredded, but after a quick cleaning out the other sensor fit in nice and snug. Thanks for everybody's input!