P0031 code

I have a 04 SR% with 3.4. Put a 02 URD 02 simulator on the rear sensor Code of P0031 appears. Front 02 sensor replaced with new Denso sensor Codes cleared 5 seconds later code P0031 code again. Help

 

P0031 is registered as a fault in the pre-catalytic converter O2 sensor heater.

Your post is a little vague as to what you did. Could you explain a little better for us? If I am correct, you are saying that you replaced the post-cat sensor with a simulator, and replaced the pre-cat sensor with a Denso sensor?

You will need to get a wiring diagram for the pre-cat A/F sensor so that you can check the heater control circuit and see if your new sensor is bad, or if there is something with the circuit, or control side. I am not at my shop, so I don't have access to a wiring diagram right now.

 

Thanks for the response.
My guy who put it in thinks it is because it is a aftermarket sensor. He is getting a Toyota OEM sensor and put it in. If that does not work the testing will begin. Have you heard of this before? What I mean it the aftermarket part not working and the OEM working. If this fix does not work going into the wiring under the dash. Millage went from 25 to 9 when the check engine light came on.
Any advice would be very much appreciated.
Thanks for your help. This is a great forum

 

OP - if you find the wiring diagram for the front A/f sensor please share it!

I'm going through some MPG/trouble code issues and need to test if the sensor is functioning correctly. THANKS!

 

Happens all the time, Toyota and Honda vehicles don't work so well with aftermarket emissions parts....very long

 

Which vehicle are you wanting the wiring diagram for. I have them all. Please post specifics.

 

What does your doodle-pad have to do with this topic?

 

'01 DC TRD 3.4 auto

Thanks!

 

My bad, I should have known to be more specific. lol

I will be in my shop on Monday and will see what I can do for you.

 

Put the TOYOTA OEM 02 sensor in. Code cleared and all is well. Thanks for all the advise. Will use this forum again.

 

Okay I have the dreaded P0031 code and have picked up the Toyota O2 sensor. I tried to put it in today and found the wire goes up over the transmission and there it disappears. The new sensor has what looks like a plug to go through the sheet metal, but I don't see its destination.
Who has photos or some instructions of where to route this?

 

Well no one jumped in to help so I searched a little more. For the benefit of the next guy doing this I learned I had to remove the shifter rubber boots assy to get to the connection from on top of the transmission.

Thursday I tried to install the new part and figured out the Toyota guy gave me the wrong sensor so they had to reorder. This afternoon I picked it up and put it in and I hope the CEL goes off the next time I drive it.

Edit: After driving to and from work 2 days the CEL light turned off. Yea!

 

Getting to the sensor and removing it is easy, at least if the bolts are not rusted. Getting to the wiring connector on the other hand is a real bear. Why in the world did they put it in such an inaccessible location? Removed my shifter boots and still could not even see the connector. I can feel it mounted to the top of the transmission but disconnecting and reconnecting it requires a a deft hand. The job could be so easy otherwise. Hope I never have to do it again!


2004 Tacoma 4 wheel drive with a manual tranny