I do not have a cat on my headers or downpipe and I get the CEL. However, I cannot fit an anti-fouler because of where the bung is located.
Does anyone know if there is some kind of "dummy" O2 sensor that keeps the correct MAF settings?

I have been running without the second sensor and I think i might be too rich cause my RPM's seem pretty low.
Sometimes to the point of almost stalling it feels.

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The Primary O2 sensor (the one before the cat) is the one that corrects the ECU with air/fuel readings, the Secondary O2 sensor (the one on the S-pipe) just detects if the cat is working. I
f you are getting a CEL, and it is idling rough, and such, then that means the car is in LIMP mode, where it is running rich for safety. And you'll know if your running rich if your exhaust is black.

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In your opinion, what is my best solution? Yes, my tip is black.

 

If you can't get the secondary O2 Sensor to fit in the pre-made bung, then have it closed off and have
another bung put in somewhere that you can plug the O2 Sensor into, and run an anti-fouler.

What kind of S-pipe is it that you can't get the Secondary O2 Sensor to fit in there?

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