P0031/P0051 Fix

I posted a thread about my "new" truck purchase. In that I mention the problem I was having with getting P0031 and P0051 error codes. Now I am posting the fix (in my case at least). If anyone else gets both codes at the same time.

1) I grabbed the FSM from this thread. http://www.tacomaworld.com/forum/2nd-gen-tacomas/89275-05-tacoma-repair-manual.html

2) Found the section for my error codes.

3) Followed it down to the place where both codes meet (AF Heater Relay).

4) Found where the in cabin relay box was located. (Picture below behind the battery).

5) Found the correct relay for the AF Heater- Pulled it out. Man It's a bitch I tell you. In the picture below the AF Heater relay is circled red.

6) Pulled the Fog lamps Relay circled in gray (I tested this one an it was good- fog lights worked)

7) Switched them.

8) Restarted truck. No CEL. No battery clear. Truck is suppose to clear the CEL after start up once condition is cleared.

9) Drove around. Restarted a dozen more times. No CEL.


Hope this helps you.

 

Thanks for posting the code and solution...
I just got this code today. Did you replace the upstream
o2 sensors first? I thought this code was to just change out the sensors. Why did you end up changing out the relays?

Thanks,

 

The relay test was less expensive (free) and once it was corrected the codes went away. I have not had them again since. The reason I did not just replace the O2 sensors is I found it odd both would go out at the exact same time, also when I had the code read, the guy at the autoparts place thought it odd as well. So the relay was the common meet me place for both of these.

 

Of course, two wouldn't go out at the same time. Genious! You just saved money for two sensors that you wouldn't been able to return. I have just trouble code P0031. Not P0051. I just wish I knew which side of the engine it is on. The repair manual doesn't say. Just says upper and lower.

Does anyone know?

 

DTC
P0031
Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)


HINT:
• • • •
Bank 1 refers to the bank that includes cylinder No. 1. Bank 2 refers to the bank that does not include cylinder No. 1. Sensor 1 refers to the sensor closest to the engine assembly. Sensor 2 refers to the sensor farthest away from the engine assembly.

1GR-FE

 

I just popped 5 codes p0031 p0051 p0037 p0057 and p0430
and this is after I had trouble starting the truck would the efi cause these codes to all come up at the same time? Also the truck has no power like it is in limp mode, it ran fine then all of a sudden it started to run really bad any help would be appreciated

 

Is there something in your exhaust pipe. None of those codes have anything to do with transmission issues which will put you in limp mode. All have to do with cat issues, but I would not think a failed cat would make the car limp, however, a stopped up exhaust system might.

 

Im gonna try and replace the af heater relay and see if that clears the symptoms, toyota said total cost would be over 4 thousand. The truck ran fine then within 24 hours started running the way it is, Im thinking that the cats are fine it only has 69k miles.

 

I did what you did and replaced the air fuel relay and cleared up the problem, tjanks for the post saved me some major dough

 

I also had error codes P0031 and P0051. After reading this post, I replaced the aforementioned AF relay and the CEL cleared (needed to disconnect battery to reset CEL).

Thanks again.

 

He is referring to the fuel air mix " Limp Mode ". This is where the system stays in an Open Loop and will run like shit and consume gas like crazy but it will get you home, usually. The fuel system is not adjusting A/F Ratio to the feedback from the sensors.

 

This did not work on my truck :/

 

i appreciate the guide, it got rid of my light .

 

Thanks for the post on using the fog relay to test the heater relay. This worked for me and saved me many hours of trouble shooting. I picked up a new relay at the local ABC autoparts store and now everything works and the check engine light went off.

 

Thanks a lot, I had the same issue, same codes and fixed it with the relay swap. In my case I didnt had the fog relay but I swapped with the Horn relay. In my case this error appeared just after I washed the interior with a Karcher.

 

Thank you for this ! I just got both P0031 and P0051 codes on my 2014 Tacoma. Figured it was something easy like a relay. On my truck, however there is a second relay box behind the fuse box under the hood. None of them are labeled though. Are these extra relays? They look similar to the relays used for the heater. If anyone is certain, please give me a response. Much thanks!

 

Look here: https://www.customtacos.com/tech.ol...oyewd/06toypdf/ewd/2006/tacoma/f/em01d0up.pdf

Relay box # 2 ( Engine Room R/B No. 2 )

 

Those five codes are for the emissions system. I have the same codes coming up on my truck and I keep resetting it with my ultraguage. I did have Toyota check it out and the say I need to have the charcoal canister that's on top of the gas tank replaced, parts and labor would be around $800.

 

The pictures are nice but in my truck, the layout for the fuses is much different, which makes sense, since it's a newer modem. However I feel like theres a different issue going on than just it being relays. Its weird to have the same relays going bad all across different years of this vehicle in the same circuit. And with these codes I have a CEL and traction control off light. What does this relay have to do with traction control?

 

Not to dig up an old thread but I’ve been battling this issue for a while now. The relay issue didn’t help me. So assuming worst case scenario I went ahead and did the 02 sensors. They looked original so why not at this point. Any other ideas or possible fixes for this? I’ve tested all efi fuses and all checks good. Is there a chassis ground somewhere I’m missing that might be affecting this?