I just bought a '10 2.2L Flex Fuel model. My flex joint/pipe needs replacing and I just noticed that I have 2 cats on it. I also see that one of the O2 sensor locations is empty. Should I have 2? I want to find out before I proceed. Thanks so much for all input!

 

Welcome to the site, You should have two O2 sensors, one upstream , before the cats, the other either in between the two cats or downstream after the second cat.

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I moved this to new thread, the other was five years dead.

 

Some cars have the "pre" bung on the exhaust manifold. The "after" should be between the cats (only the first cat is monitored).

Is the bung empty, or filled with a bolt?

There should be a wire flailing about and a CEL.

The "pre" sensor monitors the Air/Fuel ratio, that data is used to adjust the injectors. If that one is bad/missing you will be getting horrendously poor MPG and a CEL.

The "after" sensor monitors the health of the cat. If it is bad/missing you would have a CEL.

If the bung is empty, that could be the noise etc. like a cracked flex pipe and a CEL.

 

The 06's had the bung in the exhaust manifold, the '07's thru '11's had the 1st sensor in the pipe after the flex pipe before the cat.
And yes , Don the 2nd bung is after the cat or in the '08's thru '11's after the first cat.
I'm wondering if this is an after market piece with an extra bung?