O2 sensor

[Ehab]

Guys, what will happen if I removed the upstream o2 sensor

 

[jeremyc74]

Your engine won't run right. Forget this idea completely. The upstream sensor is used for A/F ratio trims and the ECU will default to a very safe, very rich map without it. That means lower power, worse fuel economy, and higher emissions.

Why would you even consider doing this?

 

[meRockboost]

You will become sterile.

 

[Ehab]

O2

Thank u guys for answering actually I have a P017 and I have try every thing but nothing worked.

Toyota 4runner 2001SR5 149k last OBD2 code P0171 sys too lean maintenance done:
1- New MAF sensor
2- New o2 sensor
3- New Air filter
4- New fuel filter
5- Cleaned fuel injectors
6- Cleaned fuel tank
7- Cleaned throttel body
8- No vacuum leak
9- No exhust leak
10- Removed catalytic converter
11- Newsomething? spark plugs
12- New spark wires
13- New PVC vulve
after all of that nothing sames to work I still got P0171 check engine along with VSC lights too. The car sames to work fine with no symptoms except for very bad fuel consumption full tank around 260mil

 

[meRockboost]

Now you ask a real question! You should have started out with that. Sorry, I don't have experience with that code but this is what I could come up with.

http://www.toyota-4runner.org/3rd-gen-t4rs/141851-p0171-lean-bank-1-question.html

 

[Sisente]

Your check engine light will come on, and probably the vsc track/vsc off lights. How do I know? Just had this, and two other sensors replaced. $1,000 worth of work.