O2 sensor question

I replaced the stock headers with doug thorley long tubes and of course the engine light came on. The stock o2 sensor seized on the driver side. My question is i am wondering if it is the upstream or downstream? i have looked around but didn't come across anything. also where is a good cheap place for an o2 sensor? i read that denso is oem so i wanted to go with them.

Thanks for any help!

 

bump

 

Go to an autoparts store and have them read the code for you. That will tell you which sensor it is.

 

i bought both of my down stream denso 02s for 50 bucks a peice on Amazon. plug and play. but upstream cost $$ like 150 last time i looked

 

Why do you think the sensor seized? A code after header install is most likely the downstream sensor, since the AFR on the upstream should still read properly - or be able to adjust for the slight change with the headers. It's the downstream that will throw the code now that the cat is gone. It's sole purpose is to make sure the cat is doing its job - which it now knows it's not.

 

i'm not sure why the sensor seized up. when i reinstalled the o2 i used anti seize and it was the first time they had been removed so maybe they didn't use anti seize or not enough from the factory. i will check out the engine code today thanks for the help!

 

Have you thought about an URD 02 SIM?

 

Ah - I thought you meant the sensor itself stopped working. Just be extra careful not to get anti seize on the sensor part of it.

I haven't followed too much of this subject on the Toyota forums, but a trick we would use to also fool the downstream sensor was to use spark plug fouler extenders, with steel wool stuffed between them. This worked well for me. It basically pulls the sensor out of the direct stream, and muffles the gas content to make the sensor read as if there was still a Cat there.

 

DO you have a pic? im interested

 

Basically, you need the size foulers that are the same thread as the O2 sensor. 2 per side. You drill one out so the O2 fits in it, and you screw that one into another with steel wool between 'em. Not sure how the ECM on the Toyota will read it, but it worked with the Dodge, which has a very sensitive ECM system.