Old oxygen sensor removal

I'm trying to replace the upstream oxygen sensor on a 1996 Tacoma. I applied rust dissolver to the nuts in picture 1, rinsed, repeated, and they aren't moving. I think it's a 10mm but my socket isn't going on.

I assume a mechanic could get the nuts off? The mechanic is booked a week in advance so I'm trying myself first but I'm skeptical I can do it.

Secondarily, how does the clip in picture 2 come off?

 

As for the nuts, they are too rusty to fit a 10mm freely. See if you can't pound one on with a hammer. If not, go up to an 11. When dealing with rusty crap heat is always your friend. if you have a propane torch heat up the nuts in hope that they expand and loosen off of the studs just a little. IMO they honestly dont look that bad. If they aren't going anywhere DO NOT force it. They have gone through countless heat cycles and are very brittle. Take it in before you snap the studs. For the connector there will be a little tab somewhere on it that you will either press down or up and then wiggle it apart. Seeing that there is a lot of debris in there try blowing the connector out with air and see what you can get out before trying to separate. If you can't get them off or just don't trust yourself take it into the shop. Paying a shop to get two rusty nuts off is going to be a lot cheaper than paying a shop to replace a piece of your exhaust. Good Luck!

 

Well you might need some heat if you have a Oxy-Fuel torch when new those nuts were M8 so use a 12mm socket .

do you have any of those sockets for rounded hardware? Heat and needle nose vise grips ??

On the connector there should be a clip on the right side that you press in to release.

Just what is all that slop on the truck around the connector ? Enough of that worked inside your connector might be your problem

 

My nuts were completely rusted round. I hit them with PB blaster for a few days, then filed them down with a small file so I could get a smaller sized wrench around them. I didnt have access to a torch or grinder. Cleared up my P1135 code.

Clip comes off with a flat screw driver. You pry the clip retainer open slightly and them pull them apart.

Use the OEM O2 Sensor (Denso). People have reported problems with after market garbage.

 

I used vice grips to remove studs, rusty ruts and all.
Bought m8 x 1.25 exhaust studs, antiseiz and m13 nuts before hand.

 

Penetrating oil, heat it with a torch until it's real hot, hammer one of these guys on: Give the end of the socket wrench some light blows with a hammer. Should come loose, the threads on the studs don't look too bad.

 

I tried pounding on a 10mm crescent wrench with a hammer, but it's not going on at all, and I can't get a good swing with the hammer because of where it is. 11mm is too loose.

I tried heating a nut with a butane torch and using locking pliers, nut won't budge, I got some good force on it but the pliers couldn't hang on without slipping because the nut shape is so bad I guess.

Penetrating oil and a bolt extractor set sounds like it's worth a try.

I don't know what the gunk is around the wire clip. It's all over everything under there. Maybe if I can just get the clip loose I could try cleaning it and see if that solves the problem? Any cleaner I should spray on it if I can manage to unclip it?

BTW the fault codes I'm addressing with this are 1. oxygen sensor slow response, and 2. oxygen sensor circuit malfunction, both bank 1.

Should I avoid driving it except to the shop? It was running okay when it threw the code on a long drive. Only symptom was a slight rough acceleration around 20mph.

Does a new oxygen sensor include nuts? I haven't bought one yet, waiting to see if I can get this one off.

 

No new nuts come with sensor
Sometimes you won't get a gasket.
You will here
https://densoautoparts.com/find-my-part.aspx

 

I need it fixed ASAP, so if I'm buying anything it's going to have to be locally in the next day or two from the auto store or hardware store. Otherwise I'd rather wait a week for an appointment with the mechanic and know it will be fixed that day.

Are we sure it's M8 bolts? Anything special about the bolt, or any bolt called M8?

What's the gasket for? Is it called something specific?

This is starting to sound way over my head.

 

M8 is the diameter = 8 millimeters
1.25 is the thread size.
The gasket is an O2 sensor gasket.
The studs (not bolt) are threaded into the exhaust flange and are replaceable. M8 x 1.25 x 24 mm.

 

The gasket keeps exhaust gases from leaking past the sensor and causing an exhaust leak. It's a pretty straightforward job once you remove those nuts. If you're planning on keeping the truck I'd use the Denso sensors. The cheaper ones just don't last in my experience.

 

It started life as a 12MM nut. I has seen them completely rust off and have the sensor dangling from the wires. You may well be able to remove them with a pair of water pump plyers.

 

Sometimes it is faster to remove the converter and get things down where you can work at them.

If the nuts break loose on the manifold.

I replaced many of those studs and bungs over the years

 

This is actually a simple repair, even for shade tree mechanics.

1. Buy OEM Front O2 Sensor and O2 gasket for your year.
2. Buy OEM nuts for your year. Google around for proper nuts. (you dont need studs unless you plan on breaking them).
3. Buy a small file
4. File down the rusted nuts so you can get a smaller wench around them. Take them off.
5. Unclip and remove the old 02 Sensor and gasket
6. Clean gasket surface
7. Install new gasket and new O2 sensor
8. Apply anti seize to the studs
9. Thread new nuts on the studs by hand and torque down to factory specs
10. Connect the wiring harness

Have a beer. This will cost you around $125 in parts. Having this done at a mechanic will be at least double.

https://www.youtube.com/watch?v=98rZ05rTUrU&ab_channel=After7Garage

 

So I bought some jack stands, wheel chocks, penetrating oil, and nut extractor sockets.

I sprayed penetrating oil, waited, repeated, tapped the nuts to help it as the can suggested, repeated, hit it with a butane torch a while, and tried various pliers, wrenches and bolt extractor sockets to try to get both nuts off. After a few hours of that all I'm doing is shredding the nuts down smaller and rounder. For a while I kept doing this with the goal of shredding the nuts all the way down until the rest falls off, but I don't think I can do that without destroying the studs.

I tried filing the sides of the nuts but I can't seem to file them down enough to get a grip on them because I can only use the file on one side because there's not enough room to move it and only one angle I can get the wrench on.

I'm feeling sick from all the fumes and the gunk and chemicals in my eyes, so I'm taking a shower and break for the day and hope I feel better tomorrow to try something else.

Mechanic still can't see me for another week.

 

What I’ve done in situations like that is cut strait down on the nut following the stud as close as you can, be careful and don’t cut into the stud. Then take a small punch and hit the nut to get it turning. The pic was for demonstration and I cut to deep. It could be done with a dremil tool on what your dealing with. good luck

 

If you're going to go destructive, why not get a nut splitter?
https://www.amazon.com/SDENSHI-Spli...&keywords=Nut+splitter&qid=1631585880&sr=8-53

 

Glad I have a CA truck

 

Ok, I took the nut splitter suggestion.

I got the nuts off the studs, by cranking the nuts with the nut splitter and trying to turn and tear the torn up nuts off with some pliers, repeating the process a couple dozen times over the course of a few hours today, but I partially stripped the stud with the nut splitter, and I bent the stud with the pliers.

I want to cry. This is getting worse and worse. Now with the damage I likely need to have the studs and the exhaust pipe replaced that they're welded to.

But I might as well try pounding the stud back straight enough that I can try to pull the sensor bracket off. If I can do that, then it's just a matter of if I can manage to get a replacement nut on that bad stud all the way. I'm trying to bend the stud back with a hammer but can't a good swing from any angle while under there, and I'm afraid I'm going to smash what's left of the threads. Maybe cover it with something to protect the threads as I hit it, but I'm not sure what. So I'm resting a bit and will go back at it soon if there's some way I might be able to bend it back enough.

If that doesn't work, can I even drive the truck to the mechanic with no upstream oxygen sensor or am I destroying the catalytic converter?

 

Update, got the stud straightened with a long socket extension. Leverage!

Gonna try to install a replacement oxygen sensor etc shortly. I hadn't bought the actual replacement stuff because I wasn't sure, but I'll ride down to the auto parts store. Wish me luck! The questions now are getting the nut on that stud, and whether this fixes the fault codes.

Thanks for all your help so far, guys. I really do appreciate all the ideas. When I have a problem like this I can't get my mind off it, and I stress out and can't sleep until it's fixed. I really really want to get this done in the next day.