O2 Sensor Identification & Clarification

EJD

EJD

TJ Overlander
Supporting Member
Ride of the Month Winner
Joined
Jul 16, 2016
Messages
1,965
Location
Oregon Coast
I'm new to O2 Sensors and have recently discovered I apparently have a Cali-emissions Jeep with the 4 O2 Sensors, i'm looking to replace my upstream sensors as I believe they make be affecting a couple of things and I needed some help ID'ing which ones are which.

https://ibb.co/hFwagF
https://ibb.co/cn4sva
https://ibb.co/m9Zsva

Can anyone tell me which sensors are in the photos I just took? I'm not sure if i'm looking at upstream or downstream...or which ones are Bank 1 and which are Bank 2? I didn't just want to assume anything so I figured i'de ask.

Thanks!
 
Last edited:
Oh... I misunderstood. I see what you're asking now.

Oxygen 02 Sensor FAQ and Information - JeepForum.com.jpg
 
  • Like
Reactions: brown_mule and EJD
Dude, thats perfect! I could not find that diagram anywhere...
Thanks!
 
EJD said:
Dude, thats perfect! I could not find that diagram anywhere...
Thanks!
Click to expand...

Haha, no problem! I was just confused. I thought you were asking which parts you needed, when you were actually asking which O2 sensors go where. I understand how confusing it can be with the Bank 1, Bank 2 stuff.
 
  • Like
Reactions: EJD
Chris said:
Haha, no problem! I was just confused. I thought you were asking which parts you needed, when you were actually asking which O2 sensors go where. I understand how confusing it can be with the Bank 1, Bank 2 stuff.
Click to expand...
So the upstream/ downstream, that's in relaishionship to the Cat? I only ask because I've seen them labeled pre-cat/ post-cat.
 
brown_mule said:
That's the diagram I used when I replaced mine.


Sent from my iPhone using Tapatalk Pro
Click to expand...
You also have a Cali version?
Chris said:
Haha, no problem! I was just confused. I thought you were asking which parts you needed, when you were actually asking which O2 sensors go where. I understand how confusing it can be with the Bank 1, Bank 2 stuff.
Click to expand...
Yeah, I initially just thought there was 1 up and 1 down...but I guess i'm one of the lucky ones with 2 on each side!

Is it best to replace both ups or both downs at a time? I'm just trying to be proactive about replacing old sensors (160k), and i've been having some weird stalling issues, i've been told I might be running rich.
 
It used to be easier when there was only one upstream and one downstream, it was only the upstream O2 sensor that affected the fuel mixture.

But we have been blessed by the EPA so that we now have four O2 sensors and any of the four can now cause fuel mixture problems. So as much as it pains me to say this, I'd replace all four. Make sure to only use NTK or NGK brand O2 sensors. Bosch O2 sensors are well known to not always work correctly in our Jeeps.
 
  • Like
Reactions: Chris and EJD
I also agree with Jerry. I would replace all 4 sensors at once. It's painful, but new one should last you at least 100,000 miles. Plus, that way you'll have the peace of mind of knowing that another one is not likely to go out right after you just repalced one of them.
 
  • Like
Reactions: EJD
They're all on order now, and have the ones on the TJ soaking in penetrating oil as we speak.
 
Ok, got all 4 sensors in the mail, all 4 sensors on the TJ came out relatively smooth with minimal hand wounds, lol.

3 of the 4 sensors went in correctly, but one did not match. So there may be a discrepancy for the Upstream Bank1, Sensor1.
The B1S1 on my '00 has notches which I will call (9 o'clock and 6 o'clock) on the wiring connector.

NTK 23122: Has notches at 9 & 6 but the wires themselves are only 10" long, and I need a 18" harness to reach B1S1.
NTK 23099: Has notches at 9 & 7 but has the correct length of 18". (Rockauto.com also lists this as a B1S1 for Cali-emissions).
NTK 23506: Is listed as an Upstream but is for B2S1, and is only 14" long...

I need an O2 with the connector of the 23122 with the length of the 23099.

Anyone have any idea if NTK 23151 would work? It looks like what I need specs and shape wise but when I enter my vehicle info, it says its not compatible with my year, but is with 97-99's for B1S1. https://www.ngk.com/product.aspx?zpid=19150
 
Last edited:
NTK 23151: Confirmed as identical to what came out of my '00 B1S1.
 
Has the NTK 23151 worked for you? I'm in the same boat you were in with the 2000 TJ B1S1 sensor. Was thinking about ordering the 23122 and lengthening the wires, but if the 23151 works, that would be easier.
 
Jerry Bransford said:
It used to be easier when there was only one upstream and one downstream, it was only the upstream O2 sensor that affected the fuel mixture.

But we have been blessed by the EPA so that we now have four O2 sensors and any of the four can now cause fuel mixture problems. So as much as it pains me to say this, I'd replace all four. Make sure to only use NTK or NGK brand O2 sensors. Bosch O2 sensors are well known to not always work correctly in our Jeeps.
Click to expand...

So, the good news is, (on my 2000 Jeep wrangler 6 cylinder) I replaced all four O2 sensors, the ignition coil, all new iridium plugs, and a new battery terminal bolt. Bad news is, it runs worse. Feels like the timing is screwed up or something is misfiring. Is there some sort of reset I should be doing after putting all that new stuff in? Little disappointed after all that work and thinking it is going to run like crazy. Any input is appreciated. Thanks
 
Chris said:
Upstream is before the cat(s), downstream is after. So the answer is yes.
Click to expand...

Jerry Bransford said:
It used to be easier when there was only one upstream and one downstream, it was only the upstream O2 sensor that affected the fuel mixture.

But we have been blessed by the EPA so that we now have four O2 sensors and any of the four can now cause fuel mixture problems. So as much as it pains me to say this, I'd replace all four. Make sure to only use NTK or NGK brand O2 sensors. Bosch O2 sensors are well known to not always work correctly in our Jeeps.
Click to expand...

I have a crazy question, my 2000 TJ only has 2- O2 sensors (1upstream and 1downstream). I"m reading about everyone having 4. Is it possible some models have only 2? I checked under the throttle body and all over the engine, I don't seem to find any Oxygen Sensors, other than what I stated. Both of my sensors are further down the exhaust. One before the cat and one after.

-I'v reviewed a few videos and forums and most have 4.
 
  • Like
Reactions: Jerry Bransford
Top Bottom
Back