try buying an O2 sensor socket maybe and soak it in every penetrating spray there is

 

Couldn't get mine out either
I'm goint to try again today with a LONG extension and a big braker bar.
I'm looking at it as justification for a header!

Cory

 

Yeah, I had a bitch of a time several months ago trying to get mine out. Make sure you spray liberal amounts of liquid wrench on there and let it soak for awhile. Cut the wire of the O2 sensor and use a 3/8"drive ratchet with a deep socket. Another idea, is to use an impact driver with a swivel head and a few extensions.

 

Mine was stuck.. I found this to be helpful:

Get an o2 socket, some extentions, and a wrench/wratchet.. Make sure the car is cold..

Turn the car on.. Keep applying torque to try to unscrew the sensor.. As the exhaust heats up, the expanding will make it easier to break loose..

NOTE: Once it's broken loose, turn the car off!!!! You do *NOT* want to completely remove the sensor while the car is running!!!!!

-Tesla

 

I was able to take mine out rather easily. I used an O2 sensor socket, and a 4 foot breaker bar. Came out first try with very little effort...Just goes to prove that there's nothing that cannot be removed with a 4 foot breaker bar...

 

I got mine loose today!
I barrowed a longer extension and a sliding-T bar from work and with a good ammount of torque- POP! and it threadded out very easy.

TIP: either cut the wire before you brake it loose OR it will break loose on it's own. I recomend cutting it as opposed to trying to get the connector apart. The harnes side is short and right behind the throtal body (I.E. a BITCH to reconnect)

Cory
Glad Bosch included a dab of anti-sieze on the threads of the new sensor.

 

I got mine out easy, actually too easy. I used the right sized wrench and it loosened right up.

You may want to try some WD-40 or some other penetrating lubricante and let it soak.

 

I had to get under my car to get mine off. I wasn't aware that an O2 socket was available until I got mine out

I used an open end wrench and used pure brawn to get mine out!
I didn't notice that much improvement after changing mine. The old one even went through two ATF treatments! I think the thing was bullet proof.

 

The O2 sensor doesn't really effect your cars performance. Most race FC's use headers that don't even have the threaded hole for the O2 sensor. Its used for emissions purposes. Without the O2 sensor the ECU just sticks to the programmed fuel maps.