Ok. My 99 Civic is straight piped from the manifold back without a Catalytic Converter.

And the car will not pass emissions without the O2 sensor plugged in to the Cat.

So I was wondering, My intake has a hole where the O2 sensor fits in perfectly. I plugged it in and the car still runs fine. I would just like to know if itll pass emissions if the sensor is plugged into the air intake.

Side View of the intake before O2 Sensor plugged in.


Top view now that its plugged in


Close Up


Closer


Much feedback is appreciated. Thanks

 

The o2 sensor measures the amount of unburned oxygen in the EXHAUST. Having the sensor in the intake will cause the computer to read nothing but oxygen and will try to add more fuel to compensate. This leads to running very rich and will give horrible gas mileage and will most likely make you fail the test. Just because something fits somewhere doesnt mean that you should shove it in there...that can get you into lots of trouble.

 

I think your 99 Civic has a D16Y7 engine. If so, the primary O2 sensor should be inserted into the exhaust manifold. Is the primary O2 sensor shown in your pictures? Where is your secondary O2 sensor?

 

The other one is in the exhaust manifold

 

And What if I hook up an O2 simulator to that seonsor. Because I would rather not put my old manifold and Cat converter back on

 

Does your state require you to have a catalytic converter? If not, replacing your secondary O2 sensor with a simulator should eliminate the CEL.

 

yes, my state requires the cat converter.

 

then you are a bad person.

just get a magnaflow cat and an EX exhaust and it should go away if you put the secondary after the cat and primary before.