How much can this affect my mileage? I am only getting 14 mpg with the mods in my sig. This seems QUITE low. I haven't gotten around to changing the fuel filter or doing a seafoam or anything like that. I just want to know how big of an effect this has on it.

Thanks

 

After changing the O2's on my car my gas mileage was just the same.That was at the 60,000 mile mark,however I was already getting a lot more than 14 mpg .
I was one of the lucky ones and they came out easy.As they are pretty inexpensive I say do it .
All the best,Mark.

 

Were they bad when you changed them? I've had a bad one since I bought the car.

 

If it's bad enough to throw a code, then yes it can make a big difference.

 

The O2 sensors control the A/F ratio = how much fuel the engine uses, and whether it uses it efficiently. If the sensors aren't providing the correct feedback to the PCM, its going to mess up the A/F ratio. Misfires and exhaust leaks before the O2 sensors will have the same effect. Why would you knowingly drive a car with a faulty O2 sensor? How do you know its "bad"?

 

It threw a code. I ran my scanner and it's voltage stayed at the same point.

I am knowingly running the car like this because a LOT of people told me it was OK to do, and I canNOT get the damn thing out. I broke the tool just trying to remove it.

 

I just used an open ended wrench on mine and gave it a sharp tap with a heavy hammer,came right out.
I have heard of people having to use heat on them to loosen them up,like I said I think I got lucky.Changed the O2's when I fitted a new cat/y-pipe.

 

Soak it with WD40, can't hurt..let sit overnight, then start up the car and when it gets hot, turn it off then try to remove it while it hot.
I've had mine chew up the threads before and it wasn't in there all that tight, if fact it back out a few threads before it started getting harder and harder to turn, ended up using a dremel and a cut off wheel to cut the O2 bung off and welded a new one on...hopefully you can get it out without going thru that though doing it hot.

Usually when the O2 goes bad, it makes the car run rich...if its real bad and the voltage is way off, it could cause too much fuel to be injected and wash your cylinder walls worst case...this is something you want to fix ASAP and not continue to drive it.