O2 sensor on exhaust question.

[dugjr24]

I know that the 02 sensor that plugs into the exhaust makes sure the air to fuel ratio is correct. If I remove my cat and that 02 sensor is removed also will my car run like crap or will it still run ok. My friend has his removed but he has a fuel mgmt system, I do not. Let me know what you guys think.

 

[vault415]

With my 95 TSI I think the O2 sensor is making it run SUPER rich. I have a nice blinkey A/F gauge and even at half throttle it's on the highest green/rich LED. Everyone on here says to just take it out of the tail-pipe and wire it up under the car somewhere because if there's no cat then all the O2 sensor is seeing is really dirty exhaust air. Hope that helps!

 

[ChicagoGSX]

I'm assuming you're talking about the 2nd O2 sensor. The 2nd O2 sensor is only there to check to see if your cat is working. I don't think it is a problem to have it removed on 95's. On 96+ the check engine light will turn on. I've driven with the 2nd O2 sensor just ziptied up. If you're talking about the 1st O2 sensor then yes you will run rich w/o one.

 

[nine5raptor]

the 1st 02 sensor is the only one that is used to adjust the air/fuel under open loop feedback conditions (less than 85% or so throttle). the second sensor (behind) the cat is used solely to check for proper operation of the converter. leave the sensor plugged in (it is in the cat-back, not the cat) and you will most likely get a cel, but you may not. remove the sensor and you will get a cel for sure. it will not change the way your car runs either way.

 

[vault415]

So if I'm getting rich readings and terrible gas milage it's the front O2 sensor that would need to be replaced?

 

[dugjr24]

thanks, yes I was talking about the second 02 sensor. that makes me feel better about having it removed. Im glad it wont make my car run like ass.

 

[nine5raptor]

Originally posted by vault415
So if I'm getting rich readings and terrible gas milage it's the front O2 sensor that would need to be replaced?

most likely it does; you will also get a cel if it is out. It won't affect wot, but you'll coat the bumper with carbon and it will feel pretty sluggish at part throttle conditions.

 

[nine5raptor]

Originally posted by dugjr24
thanks, yes I was talking about the second 02 sensor. that makes me feel better about having it removed. Im glad it wont make my car run like ass.

it'll run the same, however, you will most likely have a cel, although some don't. I had a horrible time trying to get rid of mine. I used: http://www.importparts.com/importparts.filereader?3e2ecd6608bf2a242724424d361a061e+EN/catalogs/1352 for the 02 voltage circuit and my old 02 sensor for the heater element circuit.