o2 sensor help!

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10-26-2018, 05:58 PM

hfsitsshay

Thread Starter

Join Date: May 2018

Posts: 8

o2 sensor help!

I cannot find where my upstream o2 sensor is! I've looked everywhere and I've even looked online all over..Im trying to fix it myself because I don't have money to get it fixed..I have an 04 with a 3.8 engine

10-27-2018, 06:15 AM

Jeffs02rwdSS

Join Date: Nov 2017

Location: Isanti, MN

Posts: 1,279

There are 2 oxygen sensors on your car . One is located on the backside of the engine where the exhaust leaves the engine.(upstream) and the other is located next to the catalystic convertor in the exhaust pipe(down stream). Good luck .

10-27-2018, 10:27 AM

hfsitsshay

Thread Starter

Join Date: May 2018

Posts: 8

Quote:

Originally Posted by Jeffs02rwdSS

thanks! I hope that's the right one? the guy that looked at it said it's the one before the cadilac converter

10-28-2018, 07:51 AM

wht02monte

Join Date: Oct 2009

Location: Coal City,Il

Posts: 3,996

Quote:

Originally Posted by hfsitsshay

thanks! I hope that's the right one? the guy that looked at it said it's the one before the cadilac converter

The one nearest to the cat is the downstream. The upstream is basically IN the rear exhaust manifold. Certain on this.

Its difficult to even see unless you rock the engine forward. You CAN see it if you know what youre looking for but still can be hard to find.

10-28-2018, 12:15 PM

bumpin96monte

Join Date: Feb 2008

Posts: 6,064

This drawing is a nice shot of it (looking straight at the back of the engine from the firewe all side).

10-28-2018, 03:44 PM

The_Maniac

Monte Of The Month -- December 2011
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Join Date: Apr 2010

Location: Mentor, Ohio

Posts: 12,217

Quote:

Originally Posted by wht02monte

I've never had a problem seeing it. Granted, I don't have the secondary AIR injection system (which is primarily for California emissions). That may make it a bit trickier lol.