Exact tools advised to replace OBD-II M3 O2 sensors?

[Ron97M3]

Remember I have a sensor pre cat and a sensor post cat on each pipe.

I know it takes a 22mm size, but size of what?

I have a 22mm 3/8th drive tall O2 sensor socket but I believe that will stand about 3.5 to 4 inches with the rachet head and be too tall to clear the area in all the spots.

I believe there are tight clearance issues on my 97 M3 so I am interested in
hearing from OBD-II e36 m3 owners what they used to change their O2 sensors with. I also am interested in if they heated the pipe with a torch to loosen up the sensor or what as I assume it will be stuck from heat expansion and rust.

I remember reading somebody here talking of cutting down a regular open ended wrench to a stubby to length I believe. I tried to find a 22mm open end stubby alone at sears or another cheap tool store but no luck. I know I can order one for like $30 online but since I am not positive that is what is I require I thought I would ask here first.

I am planning on working on this in the next few weeks so now is the time to work out the full plan of attack.

[Braymond141]

Um, a crescent wrench works great for breaking the o2's loose. The rest can be done by finger. There's no need for special tools.

[NeilM]

Um, a crescent wrench works great for breaking the o2's loose. The rest can be done by finger. There's no need for special tools.

Any auto parts store sells special O2 sensor sockets. Not expensive. These have a square drive ratchet connector on the side and an open top to allow passage for the wires.

That said, I've never had to use mine. A full length 22mm wrench usually breaks it free, then a stubby 22mm wrench allows for more movement to unscrew the sensor until it's finger-loose. If the sensor seems to be stuck then yes, a propane/MAPP torch might help to unstick it.

Neil

[HofmeisterKinky]

I got a socket from Autozone that looks exactly like this: http://www.alltiresupply.com/p-OTC-7807.html

You need a non-ratcheting socket wrench to use with it, though.


EDIT: Beat to it by NeilM...