Upstream O2 Sensor...In a Pickle

[4'running'26]

Well, I went to replace my upstream O2 sensor (non-California spec.) and ran into a bit of a quandary.

I was humming right along, was able to unplug the electrical portion quite easily (after taking the bracket off -- 10mm by the way) but then realized that it would be nearly impossible to get the sensor itself off of the pipe before the cat. No longer are the nuts recognizable on the studs due to rusting.

I took it down to a local shop less than a mile from my house. They told me what I was afraid I would hear, "We'll have to put a torch to it and hope we can get the old nuts off and still have enough thread on the studs to get some new nuts on."

The guy was very honest, told me I would be looking at $100-$200 worth of work, especially if it got really nasty and they had to replace part of the pipe and/or make new studs. He said it might not be worth it to me.

So, what am I to do? I don't have a torch nor do I have much experience with one. The reason for replacing the sensor was because my fuel mileage has been really bad as of late and I have done the rest of the easy stuff: new plugs, wires, air filter, PCV.

Any suggestions?

And yes, I know winter blends are not good for fuel mileage, but even taking that into consideration I am still only getting 16 MPG on the highway where in the past I have been able to get 22. Completely stock.

 

[jgue467]

02 attached to cat?

Mine was attached to regular exhaust pipe before cat. Not that it matters much, but if it was on regular pipe, you could cut it all off and put a new section of pipe. Any codes on your ecu (even if no light on dash)?

 

[GrossMan]

I just had the very same experience 3 weeks ago with my downstream O2 sensor. Was all set to do it myself until I crawled under my 4Runner and found the nuts and bolts to be an unrecognizable solid mass of red rust.
I too am torch illiterate so I took it to my local mechanic.....$115. What your mechanic is quoting doesn't seem crazy, but it's your wallet.

BTW: have you cleaned your MAF yet? And was your MPG drop sudden or gradual?

 

[4'running'26]

Mine was attached to regular exhaust pipe before cat. Not that it matters much, but if it was on regular pipe, you could cut it all off and put a new section of pipe. Any codes on your ecu (even if no light on dash)?

Yeah, I worded that incorrectly in my initial post. You are right that it isn't on the cat, but the pipe before the cat so I guess that is a viable option. I haven't checked for codes. Still trying to decide on an OBD scanner, but I guess I could run it up to Autzone. They should be able to check for codes, even without a CEL on, right?

 

[TheDurk]

If the studs are all there, then it's probably not as bad as you think. (Pics would help.)

The good news is the nuts are MUCH softer than the studs. So really ugly nuts can be gotten off with a little patience and persistence. Lots of PB Blaster is always a good idea. A mini-Vise-Grip is useful. Add leverage by putting a screw-driver sideways through the jaws. Also, bash on successively smaller deep sockets and turn them until the nut rounds off again. Eventually, you crush off pieces of the nuts to the point where you can wirebrush off what's left and then restore the threads on the studs.

Even if the studs are gone, they can be replaced by bolts.

 

[4'running'26]

I just had the very same experience 3 weeks ago with my downstream O2 sensor. Was all set to do it myself until I crawled under my 4Runner and found the nuts and bolts to be an unrecognizable solid mass of red rust.
I too am torch illiterate so I took it to my local mechanic.....$115. What your mechanic is quoting doesn't seem crazy, but it's your wallet.

BTW: have you cleaned your MAF yet? And was your MPG drop sudden or gradual?

Yeah, MAF was cleaned when I did the plugs, etc about a month ago. The decrease was gradual it seems.

What did your mechanic end up doing?

I think the guy I talked to is a reasonable guy. I don't think he would gouge me, I just hate paying over $100 for something which should be so simple...but isn't when, like you said, there is a "solid mass of red rust."

 

[4'running'26]

(Pics would help.)
.

Damnit...now I have to go out for pics in the cold rain!

Be back in a minute...

 

[4'running'26]

<a href='http://postimg.org/image/ru9z6c8qx/' target='_blank'><img src='http://s28.postimg.org/ru9z6c8qx/attachment_11.jpg' border='0' alt="attachment (11)" /></a>

Looking at it more closely, the studs seems to be quite solid still.

 

[TheDurk]

<a href='http://postimg.org/image/ru9z6c8qx/' target='_blank'><img src='http://s28.postimg.org/ru9z6c8qx/attachment_11.jpg' border='0' alt="attachment (11)" /></a>

Heh. Yeah, studs look fine. My nuts looked a lot worse. I'd feel pretty confident I could get those off with just hand tools and leave clean studs. As I said, those nuts disintegrate relatively easily.

 

[jgue467]

Still trying to decide on an OBD scanner, but I guess I could run it up to Autzone. They should be able to check for codes, even without a CEL on, right?

Yes - codes can be read (if there) w/out CEL on. I'm a super cheapskate and found one on ebay for $15 out of china. Yeah, I know cheap china stuff but it works on my toyo, SO's bmw and other rigs in family and so far has lasted 3+ yrs.

I would do what Durk said, soak, soak then soak some more then try to pry/wrench/visegrip it off. Hate it when this happens!

 

[4'running'26]

Heh. Studs look fine. My nuts looked a lot worse. I'd feel pretty confident I could get those off with just hand tools and leave clean studs. As I said, those nuts disintegrate relatively easily.

Ok, feeling better about the situation now. I'll wait until temps reach at least the high 40s again and give 'er a go. I'll blast them tonight with PB Blaster (aka. weasel piss).

Thanks guys!

 

[4'running'26]

Latest update:

I have yet to get under there (other than for spraying purposes) to tackle the rusty nuts and install the new sensor.

One reason is, I keep forgetting to get some new nuts! Is there a certain spec. on the nuts I should be getting, or is giving them the old eyeball and seeing what I can find at the hardware store good enough?

In new pertaining to my CEL, it is indeed no good, the light that is. It must be burnt out as it doesn't come on when I turn the key.

I had it checked for codes in case it was throwing any and this is what I discovered:

P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control.

The guy at AutoZone thinks either my ccoolant is low (I told him it's not..."see?") or that my thermostat is sticking. I have a strong suspicion the thermostat is not sticking as I just had it replaced by Toyota along with the TB, water pump, etc. I guess it could be though.
[MENTION=10169]TheDurk[/MENTION] would you agree that it is more than likely a sign that the O2 sensor is indeed bad because it is staying in open loop longer than it should?

Thanks!

 

[TheDurk]

Latest update:

I have yet to get under there (other than for spraying purposes) to tackle the rusty nuts and install the new sensor.

One reason is, I keep forgetting to get some new nuts! Is there a certain spec. on the nuts I should be getting, or is giving them the old eyeball and seeing what I can find at the hardware store good enough?

In new pertaining to my CEL, it is indeed no good, the light that is. It must be burnt out as it doesn't come on when I turn the key.

I had it checked for codes in case it was throwing any and this is what I discovered:

P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control.

The guy at AutoZone thinks either my ccoolant is low (I told him it's not..."see?") or that my thermostat is sticking. I have a strong suspicion the thermostat is not sticking as I just had it replaced by Toyota along with the TB, water pump, etc. I guess it could be though.
[MENTION=10169]TheDurk[/MENTION] would you agree that it is more than likely a sign that the O2 sensor is indeed bad because it is staying in open loop longer than it should?

Thanks!

1. Nuts: 90179-08059 at the stealer or any M8-1.25 Stainless Steel nut you can find.

P0125 is almost always a sign of O2 sensor issues and goes away when that is resolved. I/m just surprised you don't have any O2 sensor related codes.

 

[hambob]

You have to get the nuts from toyota. I was told that they are a one time use lock nut. Mine looked worse than yours and it wasn't so bad. For your cel, could it be the coolant temp sensor itself?

Good luck

 

[MStudt]

I just replaced my upstream yesterday, and the nuts on mine where just like yours. I used some map gas to heat the nuts, about a minutes per side. I used an easy out for nuts. I was able to get both of mine off with no issues. I was concerned that I would have to replace this sections of pipe, but the easy outs worked like a charm. I did not use nuts from the dealer. I just used some M8-1.25 stainless nuts, lock washers, and some high temp anti-seize.

These are what I used.