Bank 1 sensor 2 stuck lean...

[Logizyme]

You are using the term extension in a different manner than the OP.

He means an extension on the 02 bung so that the factory style 02 sensor is not sitting as deep into the exhaust stream as it would on an unmodified SW header.

Here is the salient portion of his post that did not catch your attention:

No, I am talking about the same thing he is. I am not talking about a wiring extension, I am talking about a tube that moves the sensor further from the exhaust stream as it used to be. They are pretty common on performance applications that still require emissions testing.

[License2Bill]

The only time I unplugged the battery in the last 2+ thousand miles of driving was today when I replaced the sensor in my driveway.

I did not have any dtc's before disconnecting the battery this afternoon. The Bluetooth adapter connects to the phone and obd and displays the graph of o2 sensor conditions over a given time. The front/first/forward sensors display a sine like wave. The rear on the opposite side of the one I replaced does as well. This one shows a flat line across the bottom of the graph indicating being stuck lean.

As you can see, there is an unnecessary steel bung welded onto the one on the header.
uploadfromtaptalk1432766622084.jpg

[RF Overlord]

That's my whole point. The OP said the shop "welded an extension on the header bung." That sounds like the upstream O2, not the downstream.

[License2Bill]

This is the downstream sensor on the passenger side.

[Logizyme]

Alright, help us understand this.

You were replacing the B1S2 O2 sensor because when you watch its datalog it does not switch like the other O2 sensors and you had no DTC's or drivability concerns?

While replacing said sensor you found only one O2 extension?

Which O2 sensor position had the extension?

Hard to tell from your pic, but is the new bung just welded over the original bung or is it welded in another position and the previous one blocked?

[babbage]

This is the downstream sensor on the passenger side.

only reason they would do that is to hack catalyst efficiency. You must have told them something - no way they did that for no reason. You are better off replacing the front o2 sensors.

how old are the fronts, how many miles?

[Zack]

[License2Bill]

The fronts were brand new with the header install. Less than 5 thousand miles. I did run the headers without a tune for a little bit. Rears were replaced after getting the tune at the end of March. All sensors are OEM Motorcraft

[babbage]

The fronts were brand new with the header install. Less than 5 thousand miles. I did run the headers without a tune for a little bit. Rears were replaced after getting the tune at the end of March. All sensors are OEM Motorcraft

Ok well that's good then as the front O2's are the important ones. I think that bung they added is causing the problem. It may be allowing water to fill up in that bung extension, after a while it will get hot enough to boil off, not good for the rear sensor.

Perhaps check the wires to passenger side rear O2, is it plugged in, cable perhaps shorting out? Not sure what it should read but perhaps put a probe on it and see if you are getting 12V.

Did you find out why they welded a bung extension on?

[justbob]

That small of an extension would not affect the rear o2's in a negative way. In fact, if they were left turned on and you had no cats, it would probably register the missing cats as doing a fine job.. I bet you have a pinched wire.


Builder Of Badassery

[Windsor58]

I have gotten a P2198 code from bad gas. When that happens, I add some STA-BIL fuel stabilizer to the gas and after a few miles the code doesn't come back (I clear the code using an Aeroforce guage). This seems to happen because where I live they only sell 10% ethanol blended gas, which sucks. If it sits for a few weeks, it will cough on hard accel and that goes away if I use the STA-BIL.
I don't know if this is causing your problem, but it would be cheap to find out if its the same as what I get.
Good Luck

[License2Bill]

Thanks for the input everyone. I decided to try my luck at emissions anyhow. The guy said the catalyst wasn't ready, but I still passed. Now I can take my time trying to sort everything out.