# Possible o2 sensor issue?



## IMCauley (Oct 14, 2010)

Hey guys, lately I'll get a check engine light that will appear only after having the car on for more than 30 or 40 constant minutes and then will go off in about the same amount of time. I've also been experiencing a MAJOR decrease in gas mileage. 

I've taken it to get scanned and scanners will say the cars running lean and other times it'll say it's running rich. I had one mechanic look at it and he gave me a bull**** round-a-bout answer and "thinks" it's an o2 sensor.

What do you guys think? Any suggestions? Thanks for any feedback!


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## 06BLACKGTO64 (Oct 30, 2010)

It can very well be an O2 sensor with what you put. why do you think he is giving you a "Bull-round about answer"? didnt you bring your car to him to get looked at?


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## IcemanGTO (Mar 2, 2011)

What did the code read?
It sounds like the 02 sensors failed to me.
The replacement AC Delco 02 sensors are the best choice.

RockAuto Auto Parts


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## IMCauley (Oct 14, 2010)

Well he was just being very vague for as much money as i was paying so I was a little irritated that i didn't leave there knowing EXACTLY what was wrong, he was like "it could be an o2 sensor" lol 

well the sensor he watched on the scanner that he said was "acting-out" was the sensor before the cat on the passenger-side/right sider header. he called it bank2sensor1


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## 06BLACKGTO64 (Oct 30, 2010)

that makes sense that it would be doing that...I mean noone here can give you a definite answer, but it does sound right that it would be that sensor since the o2 sensor before the cat reads whats actually coming out of the motor.


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## Poncho Dan (Jun 30, 2009)

Whats the switching time on the O2 sensor? If it's sluggish, then it's on its way out. It's a possibility, but usually they either work or they don't.

Have you considered a vacuum leak?


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## pctek (Jul 18, 2010)

It can be the o2 sensors if your gettign a lean error in the code and bad gas mialge then the o2 sensor can ba asking for more fuel because its starving since its on the lean side.

I have a 2001 bimmer 325i sedan with 150,000 miles on the origianl 02 sensors and i got a lean code for the pre cat 02 sensors if i remmber right and was getting bad gas mialage like around 16mpg and replace the 2 02 sensors and it jumped up to 22mpg, this is city driving btw.


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## IMCauley (Oct 14, 2010)

pctek said:


> It can be the o2 sensors if your gettign a lean error in the code and bad gas mialge then the o2 sensor can ba asking for more fuel because its starving since its on the lean side.
> 
> I have a 2001 bimmer 325i sedan with 150,000 miles on the origianl 02 sensors and i got a lean code for the pre cat 02 sensors if i remmber right and was getting bad gas mialage like around 16mpg and replace the 2 02 sensors and it jumped up to 22mpg, this is city driving btw.


That's exactly what's goin on with mine! And the mechanic said that it was possible it got damaged when they did the aftermarket headers install, cause he found it weird that it was already going bad at only 39,000 miles.


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## pctek (Jul 18, 2010)

IMCauley said:


> That's exactly what's goin on with mine! And the mechanic said that it was possible it got damaged when they did the aftermarket headers install, cause he found it weird that it was already going bad at only 39,000 miles.


Right thats low miles for 02 sensors to be going out so soon. Good luck.


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