Very Annoying p1038 and p0139 CEL

I have a 2011 TRD Pro 4d 6spd with about 85k. I have been pulling my hair out trying to figure out why I keep getting a p0136 and p0138 CEL.

I first replaced my rear driver side O2 sensor, after the cat and it went away for a little bit then came back on.

Got another Autozone O2 sensor and same thing. Then I bought one from the dealer ship and same thing, CEL came back on.

Then I replaced the air fuel sensor, before the cat, and it went away for a little then came back. Several times the light will go off for a drive or two then stay one for several weeks. I never knew a CEL would go away without being cleared or having the battery cables pulled.

I have checked the wires from the sensors and as far as I can tell there is no splits or damages. I pinned out the harness with an ohm meter and everything came back as far as I could test it. What I couldnt do was heat the sensors to the specific temp and test them.

Anyone got anything else?

Right now it has toyota dealer front driver side air fuel sensor and rear o2 sensor.

Also have gottenP0031 code is a result of the bank 1 HO2S1 (pre catalytic converter heated oxygen sensor) heating element having low voltage. And Code P2196 is a result of the pre-catalytic converter oxygen sensor detecting a rich air to fuel ratio of the exhaust on bank 1.

But once I cleared the codes they never came back. Only the 136&138 come back regardless of the sensors I have put in. I have checked the temps before and after the cat and they are the same on both sides of the motor, so I assume that the cat is not clogged.

 

If there is no exhaust leaks I would suggest carefully inspecting the wiring and connectors going to the bank 1 (passenger side) downstream oxygen sensor as you likely have a wiring issue.

 

Do I have the driver side and passenger side mixed up? I replaced both the Air fuel and 02 sensor on the driver side. I did at first try swapping the post cat o2 sensors to see if the trouble code would change but it stayed the same, then I changed the sensor thinking that it was bad.

 

Bank 1 is passenger (right) side, bank 2 is driver (left) side so yes it sounds like it.

 

I would also add your truck can't be a TRD Pro (TRD Pro package was not available until the 2015 model year) if it's a TRD it would be a TRD Offroad or TRD Sport.

 

Wow, I you were right on both accounts, I swtiched the Air fuel sensors and the codes switched from p0031 to p0051. I had the one I removed and I put that one in and the CEL didnt come back on for the 15 mins I had it idling. Hopefully it stays off. I cant believe that after all the time I spent in testing the plugs and sensors I made the simple mistake of getting the banks wrong.

 

It can happen
Welcome to the forum by the way, lots of good people and info lurking on here

 

I will also add that when I tried originally switching the sensors I guess I didn’t tighten it down enough and a small exhaust leak was around the sensor which caused both the p0031 and p0051 to pop up but after I switched to the one sensor I had spare, and the leak was no more no CEL appeared.
Thanks so much Dm93!