# Can Missing rear O2 sensor cause exhaust leak?



## show_time23 (Apr 26, 2010)

Hi I have a 2005 Altima 2.5L.

There's an exhaust leak in the manifold/precat area. I was planning on replacing the manifold/precat when I noticed that the rear O2 sensor is missing. Can this be causing the leak? 

Thanks


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## jdg (Aug 27, 2009)

If it's an open hole leading from the inside to the outside, what do you think?


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## show_time23 (Apr 26, 2010)

Lol I had to ask. Great news then, $300 repair jus turned into a replacement of an o2 sensor. 

Thanks


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## show_time23 (Apr 26, 2010)

The only other owner (family friend) only took it to Nissan dealership for absolutely anything, he's a doctor doesn't know any better lol who the hell would jus remove the sensor?!

I've had it for 3 years, I can't believe it's been without the rear O2 that long.

Any possibility that I have a precat that actually only has one O2 sensor?

Thanks


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## show_time23 (Apr 26, 2010)

I only ask this because my ses light only came on about 2 months ago. Also the light turns of if I drive long distances for a few days, then comes back on after city driving.


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## show_time23 (Apr 26, 2010)

Figured it out, second O2 sensor is by the flex pipe. So it's not missing. All the pics and diagrams showed both O2 sensors near precat!


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## smj999smj (Jan 1, 2006)

Federal emissions are different than California emission vehicles in regards to O2 sensor location.


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## mando25 (Aug 8, 2015)

Im getting a P002A code, and its like a air/fuel ratio sensor or it can also be an exhaust leak, I have the same thing with my O2 sensor, it aint there.


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## show_time23 (Apr 26, 2010)

Well in the 05 Altima there is only one a/f ratio sensor on the precat (which is the mistake I made in thinking that there should be 2 and I thought I was missing one) and an O2 sensor underneath the car by the catalytic converter.

I have a P1273 code, which is also a bad a/f sensor. Apparently it could be due to carbon build up on the a/f sensor. In a couple of days I'm gonna take out the sensor and soak it in gasoline over night to clean off the carbon. I think it will work because I inspected my old precat and there is a great deal of carbon build up. This has worked for some ppl, I'm hoping I'll be one of them.

I'll let you know I do it.


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## show_time23 (Apr 26, 2010)

PROBLEM SOLVED!

Jus passed my E-test!!!! :sunglasses:

Don't know which one of these fixes did it but, cleaning my MAF was the last thing I did.

Here's what I did:

After replacing catalytic converter
-Replaced spark plugs
-Replaced air filter
-Submerged a/f sensor in gasoline overnight (cleared codes and ses came back)
-Patched exhaust leak near flex pipe/Downstream o2 sensor
-Cleaned throttle body
-Cleaned MAF

-Performed idle relearn, then I reset the ecu (remove MAF method)

Drove for a few days and SES stayed off

I hope this helps :blush:


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