o2 sensor gas mileage

my o2 sensor went bad in my truck would this have any effect on my gas mileage?

 

As far as I know the O2 sensor is just there to make sure the more emissions are going into the air that are needed. So I believe it helps relay information for the fuel injectors of the vehicle regarding rich/lean. So yes.

 

It will run like crap. The ECU goes to a preset fuel mix. It will run, but will kill the cats.

 

When mine went out I got 14 mpg! Just replace it

 

thats exactly what im gettin!! ive heard that if i pull it out and wipe the end off it will start working fine again does anybody know if its true? also its my rear sensor thats bad would it still hurt my cats?

 

then i'll need to replace both cause the front also went bad and we wiped it off and the check engine light went off so we thought it was fine.. thats what i planned to do to the back but i thought it a little fishy that toyota would let something like that happen

 

Running with a bad o2 means you will be running rich. It will make the cat work harder to burn the extra fuel. It will shorten its life. It can also set your truck on fire, since it will be running hotter than normal.
Don't wait, or try to fix the bad one, replace it.

 

Parking in grass, fuel leak, undercoating will burn,etc. I don't have any links, just stories from reputable sources, and the knowledge that excess fuel to the cat will burn. It will glow red, and will set flammable things on fire. The degree of danger is directly related to how much extra fuel it's getting.
80's GMC trucks had this problem with the truck running properly. It was a problem with the catalyst type(pellets).

 

Info on how a cat works, and fails: http://www.jeep4x4center.com/knowledge-base/catalytic-converters.htm
I'm looking for other causes, but I'm only seeing grass fire hazards, and undercoating fires, so far...

 

You failed to go to the bottom of the article. Thermal failure from excessive fuel will cause the substrate to melt... This goes well above the normal operating temp. Shielding will only help so much. The heat has to go somewhere. No air circulating after driving, or stuck in traffic, what are the odds of a fire now?

 

hey man i seen your post in 2011 about getting 14mpg with bad 02, which o2 did you replace to fix this the upper A/F ones or lower (downstream) ones

 

I'm not the OP, but the rear downstream sensors will not affect fuel mileage. The front upstream sensors will, though. Stick with OEM denso sensors from a reputable source (not ebay or Amazon). Most go through Rock Auto.

 

okay thanks man i also have lots of exhaust leaks. do you think getting new a/f ratio sensors would somewhat increase my gas mileage even though my exhaust has leaks?

 

If your exhaust is leaking at the manifolds or before the cats, you'll likely still have issues even with new sensors. If you leaks are towards the back, that shouldn't affect mileage.

 

right after the first upstream cat on both sides flanges are leaking on the bottom flange i don’t think the actual manifold is leaking, so what would you think about that, i think the cats are still good though i hit them and didn’t hear anything rattling inside