Check engine light after replacing all O2 sensors

[RONNIE GRIFFIN]

I have a 2005 jeep unlimited I have replaced all the O2 sensors, the check engine light indicates an O2 sensor, my mechanic replaced all the O2 sensors had some other guys look at it , they were stumped he threw in the towel. My jeep has sat idol for about 6 months , it seems to be all pointing at the ecm, but I have also read that it could be the pre cats please any help would be greatly appreciated.

 

[dbbd1]

The first question is- what brand of sensors were installed?

The second question is- have you checked the wiring and plugs to those sensors?

 

[RONNIE GRIFFIN]

Dont know the brand, have replaced them 3 times, what brand do you recommend, and I will follow your advice on the latter, thank you for your kindness.

 

[nk24]

NGK / NTK are the only O2 sensors that work properly with the TJ.

https://wranglertjforum.com/threads/the-official-jeep-wrangler-tj-oxygen-o2-sensor-thread.4068/

 

[dbbd1]

^ X2

 

[Jerry Bransford]

X2 on the NTK or NGK (both are the same) O2 sensor recommendation. The usual aftermarket brand pushed by the auto parts stores is Bosch which do NOT work properly in Jeep engines, they have the wrong biasing voltage requirement.

If they're not NTK and replacing the O2 sensors with NTK doesn't do the trick, it's very likely the precats. I had multiple ongoing intermittent O2 sensor diagnostic trouble codes that weren't cleared by new NTK O2 sensors. It turns out one of the pre-cats went bad and replacing both cured the O2 sensor codes.

 

[dbbd1]

^ That's where I was going, if the sensors were NTK and the wiring looked intact.


There is also a thread about the emissions on an '05/06 and heater, IIRC. But it shouldn't be tripping the CEL.

Have you read the codes that is causing it?

 

[cliffish]

X4 pull the current sensors to see if they NTK/NGK if they are new you should still see the markings. Replace with correct ones, reset codes - you can use this to read and reset the codes, cheap enough and works great.

https://www.amazon.com/gp/product/B01C3HAHCS/?tag=wranglerorg-20

 

[Rusty Rivets]

I have a 2005 jeep unlimited I have replaced all the 02 sensors, the check engine light indicates an 02 sensor, my mechanic replaced all the 02 sensors had some other guys look at it , they were stumped he threw in the towel. My jeep has sat idol for about 6 months , it seems to be all pointing at the ecm, but I have also read that it could be the pre cats please any help would be greatly appreciated.

Have you replaced the crankshaft positioning sensor and inspected the wires for it? That was a culprit for me at one time

 

[azroc909]

X2 on the NTK or NGK (both are the same) O2 sensor recommendation. The usual aftermarket brand pushed by the auto parts stores is Bosch which do NOT work properly in Jeep engines, they have the wrong biasing voltage requirement.

If they're not NTK and replacing the O2 sensors with NTK doesn't do the trick, it's very likely the precats. I had multiple ongoing intermittent O2 sensor diagnostic trouble codes that weren't cleared by new NTK O2 sensors. It turns out one of the pre-cats went bad and replacing both cured the O2 sensor codes.

X2

Also what codes is it giving you?
I have an 06 which was giving me some codes don’t remember. Replaced all sensors with ngk gave me a new code P2096 fuel trim to lean bank 1 sensor 2 post cat. Found out the cats are bad so that’s where I’m at now. I can feel exhaust pushing out through a small crack under cat 1 at bottom.

 

[L J]

... the check engine light indicates an O2 sensor ...

Which codes are present?

There is also a thread about the emissions on an '05/06 and heater, IIRC. But it shouldn't be tripping the CEL.

that is a separate issue to do with the readiness monitor

 

[RONNIE GRIFFIN]

THE CODE IM GETTING IS P0037, HEATER CONTROL CIRCUIT LOW BANK 1 SENSOR 2 OXYGEN SENSOR.

 

[pagrey]

That's pretty easy. It's the sensor, the wiring or the PCM. Probably not a NTK/Bosch issue, that wouldn't show up as a heater issue. It would be useful if you knew the initial code that caused you to replace the sensor. If it is the same you probably didn't just get a bad sensor and it's wiring. Check that harness and the connectors really carefully. From the rear sensor all the way back to the computer. Hopefully it isn't the PCM.

 

[RONNIE GRIFFIN]

That's pretty easy. It's the sensor, the wiring or the PCM. Probably not a NTK/Bosch issue, that wouldn't show up as a heater issue. It would be useful if you knew the initial code that caused you to replace the sensor. If it is the same you probably didn't just get a bad sensor and it's wiring. Check that harness and the connectors really carefully. From the rear sensor all the way back to the computer. Hopefully it isn't the PCM.

That's pretty easy. It's the sensor, the wiring or the PCM. Probably not a NTK/Bosch issue, that wouldn't show up as a heater issue. It would be useful if you knew the initial code that caused you to replace the sensor. If it is the same you probably didn't just get a bad sensor and it's wiring. Check that harness and the connectors really carefully. From the rear sensor all the way back to the computer. Hopefully it isn't the PCM.

Thank you

 

[danzy55]

X2 on the NTK or NGK (both are the same) O2 sensor recommendation. The usual aftermarket brand pushed by the auto parts stores is Bosch which do NOT work properly in Jeep engines, they have the wrong biasing voltage requirement.

If they're not NTK and replacing the O2 sensors with NTK doesn't do the trick, it's very likely the precats. I had multiple ongoing intermittent O2 sensor diagnostic trouble codes that weren't cleared by new NTK O2 sensors. It turns out one of the pre-cats went bad and replacing both cured the O2 sensor codes.

HI Jerry
My daughters 2003 TJ just got the following code P-0159 related to the O2 sensor. Is it recommended to replace all of them at one shot? Secondly do all 2003 have 4 of these?

 

[Jerry Bransford]

HI Jerry
My daughters 2003 TJ just got the following code P-0159 related to the O2 sensor. Is it recommended to replace all of them at one shot? Secondly do all 2003 have 4 of these?

Technically that code specifies the rear-most upstream sensor which is the one that sits closest to the firewall and above the small precatalytic converter. Yes all newer 4.0 engines like your daughter's have four O2 sensors.

Make sure to go with NTK branded O2 sensors, don't let the local auto parts store talk you into another brand and especially don't go with a Bosch O2 sensor. While Bosch is a good brand, their O2 sensors have a problem in our Wranglers.

For the Bank 2 (rear most) Sensor 1 (top-most) you want the NTK 23138 like at https://www.amazon.com/dp/B001PNCLHQ/?tag=wranglerorg-20

If $$$ is not a problem it wouldn't be a bad idea to replace all four O2 sensors though. They are kinda like spark plugs in that they do eventually go bad.

 

[Chris]

HI Jerry
My daughters 2003 TJ just got the following code P-0159 related to the O2 sensor. Is it recommended to replace all of them at one shot? Secondly do all 2003 have 4 of these?

https://wranglertjforum.com/threads/the-official-jeep-wrangler-tj-oxygen-o2-sensor-thread.4068/

 

[danzy55]

https://wranglertjforum.com/threads/the-official-jeep-wrangler-tj-oxygen-o2-sensor-thread.4068/

Thanks Chris this helps a ton!!!

 

[danzy55]

Technically that code specifies the rear-most upstream sensor which is the one that sits closest to the firewall and above the small precatalytic converter. Yes all newer 4.0 engines like your daughter's have four O2 sensors.

Make sure to go with NTK branded O2 sensors, don't let the local auto parts store talk you into another brand and especially don't go with a Bosch O2 sensor. While Bosch is a good brand, their O2 sensors have a problem in our Wranglers.

For the Bank 2 (rear most) Sensor 1 (top-most) you want the NTK 23138 like at https://www.amazon.com/dp/B001PNCLHQ/?tag=wranglerorg-20

If $$$ is not a problem it wouldn't be a bad idea to replace all four O2 sensors though. They are kinda like spark plugs in that they do eventually go bad.

Really appreciate thank you sir!! If I'm doing one I'll do all 4!

 

[Jerry Bransford]

Really appreciate thank you sir!! If I'm doing one I'll do all 4!

Ok all four are different so don't buy four of the one I linked to above...

Bank 1 Sensor 1: NTK 23139
Bank 1 Sensor 2: NTK 23142
Bank 2 Sensor 1: NTK 23138
Bank 2 Sensor 2: NTK 23141