Advice needed--Strategy for fixing frozen, broken, rounded Oxygen Sensor

[SoNic67]

You have now the O2 sensor out of the stream. Even if you don't have codes, you will suffer on gas mileage.
Downstream sensors are not important - they only monitor the cat converter efficiency.

 

[deadernie]

When using heat to get the O2 sensor out you need a torch that will get the bung RED hot, and then start to work it loose. Any less heat than that might help but you're not really getting the max benefit of using the heat.

 

[lobo411]

You have now the O2 sensor out of the stream. Even if you don't have codes, you will suffer on gas mileage.
Downstream sensors are not important - they only monitor the cat converter efficiency.

Ya, I'm wondering about. Frankly, I'm annoyed at the exhaust place because they knew the right way to do it and they did it the easy way (c'mon...is it really that hard/time consuming to grind down the old bung?). On the other hand, the exhaust is under pressure, so I wonder how much difference it will really make. If it was a water temp sensor I'm sure it would be fine because the water is under pressure, so is the exhaust really that much different?

Well, I'll have a pretty good idea tomorrow anyway. It's 160 mi to work, and I've been getting a rock-solid 19.5-20.5 MPG for 6 months. Any change to that and I'll know for sure.

 

[lobo411]

When using heat to get the O2 sensor out you need a torch that will get the bung RED hot, and then start to work it loose. Any less heat than that might help but you're not really getting the max benefit of using the heat.

Ya, I just had an ordinary homeowner's propane torch. I actually have an acetylene torch that I inherited from my dad with both fuel tanks, but I don't know how to use it.

Now that I know better, though...I'd give the passenger side o2 sensor one or two college tries, and if it was obvious that it was going to be stubborn, I wouldn't hesitate to drop the Y pipe. I probably struggled with that passenger side sensor for 6 hours under the car plus a few more hours of PB Blaster soaking time. It took me less than 15 mins to drop the Y pipe, and that was only because one of the pipe to manifold bolts was stubborn.

 

[koda2000]

It's crazy that the exhaust shop welded the new bung on top of the old one. Just lazy (or stupid). 3/8's of an inch may not be enough to make a difference to the o2 sensor. I guess you'll find out. On the rare occasion that I have something done for me, I watch them and stop them, if I don't like the way they're doing something, and make them do it the way I want it. After all, I'm paying for it.

 

[Flash]

That 3/8th of an inch can make a difference. The O2 sensor should be in the exhaust stream and up to temperature.

But, OP will soon see if it's worth doing anything about.

 

[lobo411]

Thanks for the replies, folks! I've been driving a lot over the last few days (my 320 mi commute, and then a hiking trip to the mountains). So far no CEL, whereas before I changed the O2 sensors I'd have a CEL/P0420 code set more or less right after I cleared the old one out.

As for fuel economy, it seems to be in the normal range so far. I got about 20.5 MPG during the first leg of my commute and 19.5 MPG on the second, but the second leg had more wide open driving (80 MPH) and more city driving than usual, so I figure a bit of a drop is to be expected.

The y pipe I ordered from Amazon was supposed to arrive by 8 PM on 6/4, but it never showed up. I ended up getting a refund from them and they told me to refuse delivery when it arrived late....but it looks like it was never actually shipped in the first place. Glad I didn't waste time sitting around waiting for a part that was never going to arrive!

 

[lobo411]

Follow up: I still seem to be getting the same 20 MPG I was getting before. Also, my CEL / code P0420 hasn't come back. I couldn't go 2 days without setting another P0420, then I changed the upstream 02 sensors that had 150,000 mi on them, and now it's gone. My thinking was that maybe the code was set because my upstream sensors were 150k mile sensors, and the downstream sensor is relatively new w/ 45000 mi. Maybe they were just too out of sync due to age?

 

[lobo411]

I'm still getting a rock-solid 20 MPG on my 320 mi r/t commute, which is something like 2.25 hrs of 70-80 mph, 1.5 hrs of 20-60 mph, and 1 hr of 0-20 mph (1 hr to go 10 mi!). Not bad...guess the bung wasn't an issue after all!

Code 0420 hasn't come back since I replaced the O2 sensors.