2006 Explorer 4.0L looking for O2 B1S2 location

[JB95JD]

I did a search with that title and only one "4th Gen"result which didn't apply.
I have looked with a good light and mirror "after the "Y" and before the muffler" and see nothing but smooth pipe.
I see both pre CAT sensors, pretty much right at the end of the exh. mani. below the firewall with the CAT's right there.

Q1. Where it that B1S2 sensor located? Is it hidden by the heat shield(s) and placed immediately at the end of each CAT and not after the "Y"? Is this why the confusion with some people saying this model has 3 sensors and others say 4 even on a single exhaust?

Q2. Since both the upstream B1S1 & B2S1 sensors are fine and those control the a/f mixture then I'm not running lean or rich, correct? This after CAT sensor has likely just gone bad and its default code is "stuck lean". There are no cracks letting in air.

Q3. If MAF sensor was bad or cracks upstream near air intake then the error code would come from the MAF or either of the O2 S1 sensors and not a S2, correct?

Q4. So really this isn't affecting my gas mileage or A/F mixture and just needs to get repaired to reset the check engine light to pass SMOG, correct? I say this because the INFO screen is showing better MPG from 14.5 to 16.1 literally overnight and upon fill-up my capapcity went from 305 miles to 349.

Q5. On RockAuto Fords are twice the price of course but I notice their tip has a significantly different design (hole pattern) as in no holes on the side, only on the bottom. While all others took the swiss cheese approach. Anyone think this makes much difference?

Thanks in advance...

 

[410Fortune]

What is the code? Is it a lean or rich code or is it a circuit failure?

Circuit failure usually means the pre heater in your hego sensor has failed

Bank one on the 4.0 sohc engine is is passenger side
Sensor two should be directly after the first cat converter which is in the y pipe
I believe? It is on the earlier sohc trucks

 

[JB95JD]

What is the code? Is it a lean or rich code or is it a circuit failure?

Circuit failure usually means the pre heater in your hego sensor has failed

Bank one on the 4.0 sohc engine is is passenger side
Sensor two should be directly after the first cat converter which is in the y pipe
I believe? It is on the earlier sohc trucks

Thanks for the reply.
Code is P2270 $07E8 Generic
Signal Stuck Lean
B1S2
Looking at the live stream data it was just barely flucuating a few points (thousands) off zero, which seems to me more of a circuit failure.
I tend to agree it is the passenger side, which I'm hearing is opposite for most Ford engines but apparently this 4.0L V6 Bank 1 means passenger side.
The cats are pactically after the exhaust manifold right under the feet of both occupants. There are heatshields stopping a good view prompting my visit here to see if someone already knew the location. The passenger side exhaust comes all the way over to the driver to run down the driver side and there is nothing on that pipe nor after the "Y". I thought maybe there might be only one "downstream" on single exhaust.

Can a Circuit Failure have minimal movement or is it non-responsive? Probably in between right? If the wires are just starting to melt I imagine could be erradic. But properly working this sensor is saying it is seeing too much fuel or more correctly not enough oxygen, so it is telling the ECM to lean out the mixture (A/F ratio). "Stuck on Lean" i'm imagining is that the sensor has seen too little oxygen for too many miles in a row and is now reporting the issue.

If the above is correct and I'm actually running rich then the ECM is not making the correction or something (fuel pump, injectors, etc...) is not responding to the ECM instructions. Then I should be getting bad MPG, correct? I have only filled up once so I can't tell but the INFO screen went from 14.5 to 16.1 MPG overnight.

I cleaned the MAF sensor the first day, so that is about the only thing I'm rulling out. Maybe changing out the O2 sensor shouldn't be the first go to move. Just inspect if wire are melting, maybe switch downstream sensors (if I can find them) and see if the problem follows the sensor. If does then change sensor if not start looking elsewhere I guess.

 

[410Fortune]

First move is to clear the code see if it returns

The way v or in-line engines are numbered
Cylinder #1 is the forward most cylinder on the block. The passenger side head is closer to the radiator/fan than the drivers, thus cyl 1-3 on pass side

Stuck lean and not switching indicates wiring issue or failed/failing sensor. Odd because it’s typically a catalyst monitor after the cat, but I suppose it does report to the pcm about catalyst efficiency
This is not the same as having an actual lean condition being reported by upstream sensors. The upstream sensors are the ones responsible for the air fuel ratio from the pcm. This is why you are not seeing a large decrease in mpg etc, sensor 2 is only a “monitor”

Physical inspection of the sensor, wiring, exhaust, (no leaks) if the code returns I would replace.

If your sohc is indeed a 3 o2 sensor engine then b1s2 would indicate the single downstream sensor (after cat)

I am not sure what years are 3 sensors vs 4 w the sohc
If there is a single sensor after the y comes together then it is a 3 sensor system

 

[JB95JD]

First move is to clear the code see if it returns

The way v or in-line engines are numbered
Cylinder #1 is the forward most cylinder on the block. The passenger side head is closer to the radiator/fan than the drivers, thus cyl 1-3 on pass side

Stuck lean and not switching indicates wiring issue or failed/failing sensor. Odd because it’s typically a catalyst monitor after the cat, but I suppose it does report to the pcm about catalyst efficiency
This is not the same as having an actual lean condition being reported by upstream sensors. The upstream sensors are the ones responsible for the air fuel ratio from the pcm. This is why you are not seeing a large decrease in mpg etc, sensor 2 is only a “monitor”

Physical inspection of the sensor, wiring, exhaust, (no leaks) if the code returns I would replace.

If your sohc is indeed a 3 o2 sensor engine then b1s2 would indicate the single downstream sensor (after cat)

I am not sure what years are 3 sensors vs 4 w the sohc
If there is a single sensor after the y comes together then it is a 3 sensor system

I clear the code every day. I comes back quicker +-10mi. in city driving, but over 60mi from a cold start when I left in the morning (showed up the next morning right away).

OK got it. The new mpg being reported could be phanton (a software glitch) as upstream sensors are not telling pcm to lean the mixture. So likely will still get the 300mi to a tankfull.

Pretty sure I have 4 sensors as I can see everything after "Y" and its all smooth pipe to the muffler.

Appreciate the help, a testing I will go.

 

[Fix4Dirt]

in your info it says you have a 97... is this right? this is in the 4th gen secion... if it is indeed a 97, my 98 at least only has 3 iirc (let me check on that one)

 

[410Fortune]

He says 06 in thread title

 

[Fix4Dirt]

He says 06 in thread title

whoops duh!

 

[JB95JD]

Profile updated, yes 2006 Explorer - Advance Trac RSC - Eddie Baurer V6 4.0L. Not sure how 97 got there, I must have been thinking of my older one.