O2 Sensor Wrench Size?

[Dolmangar]

I'm in the process of replacing my O2 sensor, and by in the process I mean

"Can't get the damn old one out".

The wrench I picked up is the wrong size and slips so I'm going to go pick up a large open end wrench to get some leverage from under the car. The largest one I have is 16mm, anyone happen to know the size I'll need? (Looks like 19 or 20mm the sensor wrench that Advance had was 7/8" and it slipped enough to start rounding the corners).

I forgot to bring the new one with me today otherwise I'd just stop and use it as a guide. I was tempted to just cut off the wire last night and hammer a socket on but though that it was probably better to at least attempt to do it right.

My torch head has gone missing on me so I need to pick up a new one anyway, I figured a good heating and a long wrench would take care of it.

BTW, '88 325is

[pharow]

I think it is a 22mm, or 3/4.

[bimmerteck]

22mm

[Aptyp]

22 or 7/8"... Sears o2 wrench is awesome.

[slammin.e28]

Twenty-two millimeter. AKA seven-eights. Mine has both stamped on it.

[NC325iC]

adjustable

[Jaxx_]

you can get a 22 for O2 sensors specifically. there's a cut out for the wire, yet you're still able to get a ratchet on it. if you can't fit that, just get an adjustable c wrench.

[foofopps]

I went to pepboys and rented a 22mm O2 socket (free) but even that is slipping and rounding the corners! The socket is brand new too I took it out of the shrink wrap. I was going to reuse this O2 sensor with my new exhaust and now I'm f*cked and have to spend $90 on a new one I think. What to do? Heat it with a propane torch and use vice grips??

[Jaxx_]

I went to pepboys and rented a 22mm O2 socket (free) but even that is slipping and rounding the corners! The socket is brand new too I took it out of the shrink wrap. I was going to reuse this O2 sensor with my new exhaust and now I'm f*cked and have to spend $90 on a new one I think. What to do? Heat it with a propane torch and use vice grips??

you could do that. did you spray it with PB plaster?

You could also just try a box wrench. You can cut the wires and then re solder them after the 02 sensor is off. depends if you seriously want to reuse that sensor or not...

[MaksV]

22mm

[NC325iC]

ive never had a problem with just using an adjustable wrench on them, of course i live in the south and theres not rust, and i always use a bit of anti seize when i put them back in.

[Adrian_Visser]

A crescent wrench on a heat seized fastener is a sure way to strip the head off fast, so is using an open end wrench.

Soldering O2 sensor wires is not optimal either because the solder will change the resistance of the O2 sensor circuit and since the signal generated is such a low voltage it is very easy to throw the reading off, of course if the sensor is old anyway it's pretty much a moot point.

Spray with penetrant, heat, repeat. An oxy-acetylene torch is your friend in this case. If the sensor can't be saved so be it, in the future spray with penetrant, heat repeat before you mangle it. A damaged bolt remover socket of the right size will bite into the fubared head and get it off quick.

[u3b3rg33k]

^^^ not for a narrowband... the connector is more likely to be an issue.

I bought the bavauto O2 wrench. It's a beautiful thing.

[Dolmangar]

Thanks for all the responses guys. I'm not really all that concerned with damaging the existing sensor since I'm replacing it but I didn't want to damage it and still not be able to get it off. The cheap 7/8 O2 wrench I bought slips, and the large adjustable isn't ideal either since it can't get a solid hold on it.

So I'm probably going to just cut the wire and put a large box wrench on it so I can get some leverage as it's really stuck on there. I don't have a good set of large wrenches so this is an excuse to fill out the tool box I guess...

If I can get a hold of a socket style wrench I might be able to put the impact wrench on it. Either way I think it's going to need some heat and serious leverage.