The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

[Foxxy]

I have a 2004 4.0 6cyl and it appears to only have 2x o2 sensors. This is from a TJ sold in australia so I’m guessing we have different laws regarding emissions.

Can anyone shed some light on which sensors I need to buy to replace my existing ones?

 

[reddvltj]

I have a 2004 4.0 6cyl and it appears to only have 2x o2 sensors. This is from a TJ sold in australia so I’m guessing we have different laws regarding emissions.

Can anyone shed some light on which sensors I need to buy to replace my existing ones?

You are correct, export TJs only ever came with 2, O2 sensors. I know some where in this thread the subject has been brought up few times. Unfortunately I can't tell you a page or a post number to look for... I know there are some other members that hail from down under that might be able to point you in the right direction.

 

[Alliance2000]

Hello everyone!

I bought a 2005 TJ Rubicon where the seller told me the CEL was on due to 4 cheap China O2 sensors - the error codes (he showed me via OBD): P0031, P0037, P0051, P0057.

I checked here on Wranglerforum and got 4 new O2 sensors from RockAuto:
- NTK 23158 (downstream, cyl. 4-6, bank 2 / sensor 2)
- NTK 23159 (downstream, cyl. 1-3, bank 1 / sensor 2)
- NTK 23160 (upstream, cyl. 4-6, bank 2 / sensor 1)
- NTK 23195 (upstream, cyl. 1-3, bank 1 / sensor 1) - this is the "newer" version of NTK 23018, the only one offered from RockAuto.
After installing them - still CEL with 3 of the 4 codes above: P0031, P0037, P0051 (read via VeePeak OBDCheck BLE+ with CarScanner App).

Today I checked all O2 wirings:
- All 4 sensor harness plugs have a common ground with good connections (G105 at lower right engine block - looks good and tight).
- All other 3 connectors of each 4 sensor harness plugs have good connections to the PCM connectors (harness side), no wrong grounds - so wiring should be good.

- When sensors are connected to the harness, the heater control pins have a connection to ground, all with 4.6 Ohm (Wrangler manual: 2-30 Ohm) - so heaters of the (new) O2 sensors should be good.

- PCM heater control connectors (at the PCM) have 3x about 75 kOhm against the PCM ground (C2 - pins 17 and 18, C3 - pin 17), and 1x about 6 MOhm (C2 - pin 18) - that’s the O2 heater control for O2 sensor 2/2 - this sensor doesn’t throw a code at the moment - would be P0057).

- With ignition on / engine off, all O2 sensors show 1.27V (Wrangler manual: 5V) - read via OBD. During engine idle, they show 0.04V - 0.06V and increase and decrease while driving (up to 0.9V).

- I swapped the ASD relay against the fog light relay (same spec), the fuse #17 (Power - 20 Amps) is also good.


Do you think that might be the PCM itself?

 

[Link]

Hello everyone!

I bought a 2005 TJ Rubicon where the seller told me the CEL was on due to 4 cheap China O2 sensors - the error codes (he showed me via OBD): P0031, P0037, P0051, P0057.

I checked here on Wranglerforum and got 4 new O2 sensors from RockAuto:
- NTK 23158 (downstream, cyl. 4-6, bank 2 / sensor 2)
- NTK 23159 (downstream, cyl. 1-3, bank 1 / sensor 2)
- NTK 23160 (upstream, cyl. 4-6, bank 2 / sensor 1)
- NTK 23195 (upstream, cyl. 1-3, bank 1 / sensor 1) - this is the "newer" version of NTK 23018, the only one offered from RockAuto.
After installing them - still CEL with 3 of the 4 codes above: P0031, P0037, P0051 (read via VeePeak OBDCheck BLE+ with CarScanner App).

Today I checked all O2 wirings:
- All 4 sensor harness plugs have a common ground with good connections (G105 at lower right engine block - looks good and tight).
- All other 3 connectors of each 4 sensor harness plugs have good connections to the PCM connectors (harness side), no wrong grounds - so wiring should be good.

- When sensors are connected to the harness, the heater control pins have a connection to ground, all with 4.6 Ohm (Wrangler manual: 2-30 Ohm) - so heaters of the (new) O2 sensors should be good.

- PCM heater control connectors (at the PCM) have 3x about 75 kOhm against the PCM ground (C2 - pins 17 and 18, C3 - pin 17), and 1x about 6 MOhm (C2 - pin 18) - that’s the O2 heater control for O2 sensor 2/2 - this sensor doesn’t throw a code at the moment - would be P0057).

- With ignition on / engine off, all O2 sensors show 1.27V (Wrangler manual: 5V) - read via OBD. During engine idle, they show 0.04V - 0.06V and increase and decrease while driving (up to 0.9V).

- I swapped the ASD relay against the fog light relay (same spec), the fuse #17 (Power - 20 Amps) is also good.


Do you think that might be the PCM itself?

Yep you have a PCM purchase in your future. My 2005 ran a long time with those codes but eventually it started having lots of unrelated codes and some running issues. New PCM fixed me right up.

Let's summon @Wranglerfix

 

[Wranglerfix]

Good morning, and thank you for the tag. One of the known issues on a six speed Pcm is faulty O2 sensor readings. You will also lose your fuel gauge, and it will stall while driving. Have you experienced any of the other symptoms?

Thanks,

Mark

 

[Alliance2000]

Good morning, and thank you for the tag. One of the known issues on a six speed Pcm is faulty O2 sensor readings. You will also lose your fuel gauge, and it will stall while driving. Have you experienced any of the other symptoms?

Thanks,

Mark

Hi Mark, thanks for the reply!

I also sent you an email yesterday with the details, but the engine is running fine and the fuel gauge is working.

Best regards,
Marcus

 

[Link]

Hi Mark, thanks for the reply!

I also sent you an email yesterday with the details, but the engine is running fine and the fuel gauge is working.

Best regards,
Marcus

In my case, when I bought the Jeep there were no check engine lights. But when I connected a code reader, I had the O2 sensor heater codes. I replaced the O2 sensors with NTK ones and still had the same codes. Engine ran great though. I talked to Wranglerfix but decided to keep running it. Put probably close to 10k miles on it. One day, I started it and it ran really rough, then smoothed out and ran fine. I checked the codes and had something like 20 different and random codes. It started running rough every time I started it. I decided it was time. Bought the Wranglerfix PCM. Put it in, crossed my fingers, and started it. Ran great. Ran it around and then checked the codes. No codes. I later did get a trouble code for the cylinder 3 misfire so it tells me the Wranglerfix PCM will send trouble codes if needed. Of course, I fixed it by wrapping the injector and the fuel injection rail with insulation as well as a new heat shield kit.

I later had to fix an issue with the instrument panel and decided to figure out why the check engine light wasn't working. I found a piece of electricians tape over the LED. So, that leads me to suspect the check engine light had been on for a long time before I bought the Jeep.

The LED is uncovered now and only illuminates when I start it.....like it should.

 

[Farmergreg]

The check engine light is the most reliable thing on a wrangler.

 

[Link]

The check engine light is the most reliable thing on a wrangler.

 

[Alliance2000]

Update:
I replaced the PCM with one from @Wranglerfix and CEL was off. Obviously the 4 emission tests were "not completed", but after 3 days of driving, finally the "O2 sensor" test switched to complete. Then after another day of driving, the CEL came on again and I got the codes:
- P0133 "Heated oxygen sensor (HO2S) 1, bank 1 - slow response" - confirmed
- P0431 "Warm up catalytic converter, bank 2 - efficiency below threshold" - confirmed

How come that even with a new PCM and 4 new NTK/NGK sensors, the P0133 error code shows up? And is the P0431 an indication of a failing catalytic converter, that just wasn't showing up due to the failing PCM before?

I also found the suction line that goes into the firewall to be fixed poorly, so I fixed it again with shrink tubing yesterday and cleared the codes. CEL is off (due to code clearing), but now I got another code "pending"
- P0457 "evaporative emission (EVAP) system - leak detected (filler cap loose / off)"

The fuel cap is not loose. This TJ is giving me headaches. Anyone some hints / ideas / helpful thoughts?

Edit: I did a video of the O2 sensors in idle - maybe that helps:

 

[Link]

You probably have several issues going on. Failing PCM was probably just one of them

I’d be looking for vacuum leaks, intake and exhaust manifold leaks/cracks, replace the fuel tank cap, have the catalytic converters tested (back pressure), and then as a last resort, consider replacing the O2 sensors (least likely issue but possible). Sometimes parts are bad from the manufacturer.

Very good chance it’s time to replace your catalytic converters.

 

[macleanflood]

Wiring and grounds.

-Mac

 

[Cloaked_TJ06]

@Chris , I have a cel on my jeep TJ 2006 its a P0421 . I cant scan it with a code reader since my obd2 port is all mangeled up but is that a sign that the cats are bad and needing replaced ? I also heard I can just buy the 2 cats and save a bit of money since the 3rd cat is not monitored by anything

 

[Chris]

@Chris , I have a cel on my jeep TJ 2006 its a P0421 . I cant scan it with a code reader since my obd2 port is all mangeled up but is that a sign that the cats are bad and needing replaced ? I also heard I can just buy the 2 cats and save a bit of money since the 3rd cat is not monitored by anything

A P0421 code typically indicates that the catalytic converter on bank 1 isn't performing efficiently, which could mean that it's time for a replacement.

As for replacing the cats, you're correct that the third cat (the one after the main cats) is not monitored by the PCM, so many people go the route of just replacing the two monitored ones to save on cost. Do keep in mind however that if you're in a state where they do inspections, you won't pass with your third cat missing. I've always lived in states where there was no emissions / inspections so it was never a big deal.

You may also want to check for any exhaust leaks or issues with the O2 sensors since those can also trigger similar codes.

 

[Cloaked_TJ06]

A P0421 code typically indicates that the catalytic converter on bank 1 isn't performing efficiently, which could mean that it's time for a replacement.

As for replacing the cats, you're correct that the third cat (the one after the main cats) is not monitored by the PCM, so many people go the route of just replacing the two monitored ones to save on cost. Do keep in mind however that if you're in a state where they do inspections, you won't pass with your third cat missing. I've always lived in states where there was no emissions / inspections so it was never a big deal.

You may also want to check for any exhaust leaks or issues with the O2 sensors since those can also trigger similar codes.

Thanks , also was gonna go with the magnaflow 2 cats not with the 3rd one to save on cost . will the factory one bolt up to the aftermarket one ? as far as the obd2 port goes is there a link to one ? mine is so far gone with wires out of it I cant get an accurate scan of anything

 

[Chris]

Thanks , also was gonna go with the magnaflow 2 cats not with the 3rd one to save on cost . will the factory one bolt up to the aftermarket one ? as far as the obd2 port goes is there a link to one ? mine is so far gone with wires out of it I cant get an accurate scan of anything

Can't say as to whether it will bolt-up or not as I have no experience with them, I'd probably reach out to Magnaflow first and ask to see what they say.

I looked on eBay and can't find an OBDII port. I know for sure you'll be able to find one on a wrecked TJ if you check: https://www.car-part.com/

That website is a nationwide database of every auto salvage yard. You can search by zip code. Find a yard with a TJ near you and go check it out. It would be easy to snag that OBDII port.

 

[espinosalvaro]

I recently change my O2sensors bank 1 and 2, 2,5cc (wrangler tj 2000) for the NtK.
The idle at first was low and it is getting regular but the jeep is releasing kind of black smoke on the scape. Any ideas?
Also change the fuel pump last year, the ILC valve.

 

[Siwash89]

I have a 2000 with California emissions. Only see the ntk 23179 available. Do i get 4 of those? The length be ok? Or do i get 2 each of the walker 250-24942 and 250-24943?

 

[Link]

Looks like you can get NTK upstream on Rockauto. It appears to me the only difference is the cord length but I’m not 100% certain. Guessing the upstream have shorter cords.

 

[Siwash89]

If anyone knows what sensors i need that would be greatly appreciated