My 2001 Montero Limited has four O2 sensors and I replaced 3 of them without any trouble. However, the last sensor - Bank 2 (driver side), in front of the catalytic converter is giving me hell. This sensor is positioned at a weird angle and there is absolutely no clearance there to get any wrench on it. I do have an O2 sensor socket, but it does not help ether. I can not get both socket and ratchet on the sensor. I can get the socket on, but ratchet bumps up against suspension support and can not be attached. Is there a trick to remove this sensor? Is there a better angle to approach it from? I'm going directly from below the truck in the space between engine/transmission and the exhaust pipe (tight squeeze). So far it looks like the only way I can get to this sensor is to disconnect catalytic converter from the exhaust manifolds on the engine. Is this the only way to do this? This little bugger has me defeated so far
Many thanks for your help.

 

Cut the wire, fit big wrench rounded end.

If wrench doesn't fit, maybe these?




Use a dead blow hammer on the wrench. If still doesn't work it may help to warm up the exhaust first.

 

The wrenches pictured above may not be a bad idea. I am hesitant to cut the wires until the sensor at least moved a little. Unfortunately there is no space for a hammer up there, or for the second hand for that matter. That what makes it a little complicated. I think I've seen the bent wrenches like pictured with 1/4 opening on the end. That might work. Will keep you posted. Thanks for the reply.

 

How did it go?

 

No matter how many times I tried, I was not able to get that sensor out on my own. There was just no room under the vehicle to get any leverage on the wrenches. I had to take it to a mechanic I trust. He put Montero on the lift. Cut the wire off the old sensor. Slipped a box-end wrench on it (the wrench had an open end cut off), then put a long pipe onto the handle of the wrench. After multiple attempts and even longer pipe he was able to make sensor rotate and break the corrosion fusion in the threads. Following that he removed it with regular wrench. Install of the new sensor was easy. When you are standing under the vehicle, the reach angle is much better.