Removing Oxygen Sensor open end or box end?
 

Hello

I am about to remove an Oxygen Sensor that has been in the vehicle for 22 years.

l plan to spray it with alot of PB Blaster Penetrating Oil and leaving it sit overnight.

I have a 22mm combination wrench that is about 12" long so I should be able to get a fair amount of torque.

Queston is: should I use the open end or the box end? The box end is 12 point.

Or should I purchase a 6 point offset O2 sensor wrench / socket?

when I replaced ones on W124 and W126 I had enough space to slide the wire through the box end and loosen it up.

you can always just check if you have enough space before buying another tool

I would think you will get better grip using the box end of the wrench.

Box end, assuming the metal hex on the sensor is still solid metal and not badly rusted away. As long as the 12-point box has something solid to grab, you should be okay.

• If you need more leverage (if you have room for it), you can slip a pipe over the open end of the wrench.
• Or use this trick: https://youtu.be/SDI4j1LgqV4?t=35 Be careful about the wrenches disengaging and pinching your hand though. In the comments, someone suggested slipping the box end of a much larger wrench over the open end of the smaller wrench, which is less prone to slip and thus safer.

The penetrating oil will wick in to the threads more if applied when the object is warm. It will wick in as the object cools. Care and prep in the event of a fire while doing this should be taken. Strike the threaded portion several times from side to side, then apply significant torque to the fastener ending with the final amount of break-it-free torque in a snapping/sudden movement. Slow and steady torque vs. snapping it loose in my experience causes rounding of the hex sides.

Good luck!!!

While removing the old sensor I’ve cut the wires off so it’d fit into a socket.

Box end of wrench on sensor, make sure its sitting nice, strike wrench with heavy hammer, it will break loose.

Perfect advice a few posts up, apply oil on the sensor when hot, it will wick it in as it cools

When replacing the sensor, using an anti-seize compound is a good idea. Use a light coat applied to the threads. LIGHT is the key word. Avoid getting the compound on the sensing element as the burning graphite can cause false readings.

X2, too little is better than too much.

murphysf, buy the offset Oxygen sensor wrench. It's always best to use the proper tool for the job. The tool is relatively inexpensive, and you will have it for future Oxygen sensor replacements.

All new sensors come with it, bosch preapply it, denso give you a vial of it in their box. NTK too.




btw - the socket can be rented for free from autozone etc. they take a deposit on it and return it to you 100% when you return the tool. Their little kit has 3 sockets in it.