Good morning all!

I've been lurking the interwebs and trying to come up with a fix before asking or asking a question that has been asked so many times before. I've been getting codes P1057 and P0138 with a CEL. I replaced the sensor with a NTK brand sensor and cleared the code. CEL went away and I went for a drive. After shutting off the jeep, picking up my daughter and starting to drive away the CEL returned. Pulled the code, Same codes as before. Check the wires, the plug all good. Clear the codes. Light is off. But it has come back 3 times again. Clears it, goes away then randomly comes back.

Is there anything else I should look for? Could it be a faulty sensor from the factory? Any and all help will greatly be appreciated. This forum has so many amazing members with a ton of knowledge

The jeep in question is a 2011 Rubicon

 

P0157:


P0138:


If you replaced that with a new sensor already, I'd lean towards the issue being electrical or the PCM acting up. It's not impossible that you got a bad brand new sensor, but probably unlikely. Do you have a scan tool that can read the live data PIDs? I only have a manual for the 3.6L, but I'd imagine that when it comes to 02 sensors this might be the same thing. I could post the troubleshooting steps if you are able to access the live data so see the appropriate values.

 

For the scan tool, I've been using the JSCAN with dongle. Still learning about jscan, but I can try and get any reading that might be helpful. I appreciate your help. Thank you!

 

I'd start by looking at what your O2 sensor voltage readings are. If you've not dug into the live data on Jscan, it's pretty easy. When conneted to the vehicle, go to Live data, hit the yellow menu button, search "oxygen", check the PIDs you want, hit ok and then hit the Play button.






I believe the normal values would be fluctuating between 2.5v and 3.5v per the theory of operation in the service manual (again, i only have manual for 3.6L, but suspect this is the same) -

Theory of Operation
The 4-Wire oxygen sensor is equipped with a galvanic battery that typically generates a voltage signal between 0.0 volts
and 1.0 volts. The 4-Wire O2 Sensor also includes a heating element that keeps the sensor at proper operating temperature
during all operating modes. Maintaining correct sensor temperature at all times allows the system to enter into closed loop
operation sooner. Also, it allows the system to remain in closed loop operation during periods of extended idle.

A bias voltage in the Powertrain Control Module (PCM) shifts the signal voltage to fluctuate between 2.5 volts and 3.5
volts, depending upon the oxygen content of the exhaust gas. When a large amount of oxygen is present (caused by a lean
air/fuel mixture) the sensor produces a low voltage. When there is a lesser amount of oxygen present (caused by a rich air/
fuel mixture) it produces a higher voltage. By monitoring the oxygen content and converting it to electrical voltage, the
sensor acts as a rich-lean switch.

In Open Loop operation the PCM ignores input from the O2 sensors. In Closed Loop operation the PCM monitors the O2
sensor's input (along with other inputs) and adjusts the injector pulse width accordingly based on pre-programmed (fixed)
values and inputs from other sensors. The PCM also compares upstream and downstream O2 Sensor inputs to calculate the
catalytic convertor oxygen storage capacity and converter efficiency.

 

I was able to find some time this weekend to run a scan. The sensor in question would have voltage then drop to 0. when it would stay at 0 for some time, the CEL illuminated. here are the readings.


Bank 1 sensor 1 0.72v
Bank 1 sensor 2 1.27v

Bank 2 sensor 1 0.07v
bank 2 sensor 2 0.00v
another reading

Bank 1 sensor 1 0.69v
Bank 1 sensor 2 1.27v
Bank 2 sensor 1 0.76v
Bank 2 sensor 2 0.00v

 

 

Sorry, I've been away for a bit. I have a feeling this is going to be leading to wiring or pcm, and in both cases any wiring diagram i have for the 3.6L is not going to be helpful, or I highly suspect it might not be. I think if it were me, I would swap sensor 2 between bank 1 and bank 2 and check the data just to confirm that the issue did not move and that it's 100% not the actual O2 sensor. I highly suspect it is not, but that is the next easiest step in my mind. I'm going to load all the pages for those two codes that I have, but I have my doubts that the 3.6L manual might be relevant when it gets to the granular level of wiring diagrams, and the next steps would be tracing the wiring and checking continuity, I think, looking for a short to ground or voltage.

Anyone else have a thought?

 

 

Thank you so very much for your help!

I spent a lot of time this weekend looking at all grounds, checking wires. All seemed ok. Cleaned the grounds up and snugged back down. I cleared the codes and set off on an hour drive, Did this twice.

While on the drive everything ran great, no CEL. I stop and shut it off, then when I fire the jeep back up, I would say within 5 minutes a CEL illuminates. Check code, just the P0157. P0138 has stopped coming in.

At this time would you suspect a PCM on its way out?

Would/is there a way to reset the PCM help in anyway?

 

I think it's really hard to say. Electrical gremlins are the worst. Outside of having a rodent issue, I'd think PCM is more likely than a wiring issue, but that is a really expensive parts cannon to throw at it. If had a proper wiring diagram for an '11, I'd first want to do as much wire tracing as possible and check continuity. Really seems like quirky circumstances that the codes are being thrown. I don't believe there is a way that you can reset a PCM, but getting outside my realm of personal experience.

@ronjenx , you are someone that comes to mind that might have a good suggestion if you happen to be around.