My check engine light recently came on. My mechanic says my o2 sensor is not working at all. I get really bad MPG and a weird idle. Everytime i would break my RPM will go up and down but never pass the 1000 mark. When i step on the gas it kinda lack power. Would this be the o2 sensor attached to the exhaust manifold? Would i need the upstream sensor? I was looking at the Denso brand. Please help!

 

The way it is running sounds like a throttle body issue.
Your car has 2 O2 sensors. But usually the rear one will not effect the running of the car much.
Do you have an ETS light?

 

No my ETS light isnt on. It does not seem like anything major. I figured it might be the o2 sensor by the manifold.

 

What does ETS mean anyways?

 

Oh boy
Are you in for a BIG ($$$$) surprise
Your MILEAGE always helps when asking a question

You may want to start reading....(start anywhere)
http://www.matthewsvolvosite.com/for...forum.php?f=12

 

ETS= Electronic Throttle System.

 

Here is where you can buy an aftermarket throttle body that is built better than the original. Xemodex Inc. Technology Improved US