Honda Civic VX catalytic converters
 

How many catalytic convertes does the Civic VX have? I am trying to verify my configuration, but getting conflicting information. The vx has a catalytic converter right below the exhaust manifold. Did it originally come with another catalytic converter in the exhaust pipe below the car?

Welcome.
As far as I am aware, no production cars have two catalytic converters in series. Cars with two exhaust systems (V8s and the like) have one on each branch.
A cat has sensors and electrical connections to it. If you remove a cat you have to fool the ECU into thinking it is still there.
I think you will find that the system on your Civic VX is as it came from Honda.
https://repairguide.autozone.com/znet...5280061831.gif

Thanks for your reply. You are probably right that the VX has only 1 cat. However, I don't think the catalytic has electrical connections. Maybe you are confusing it with the O2 sensor? Also, googling for "secondary catalytic converter" shows that some cars do have 2 in series.

Thanks! That helped quite a lot. The diagram from Autozone is much clearer than the Honda parts diagrams!

Unortunately, a car mechanic inserted a second catalytic into the exhaust pipe!

Are you sure it is a cat he fitted, and not just an expansion box? The cat is "Exhaust Pipe A" in the diagram. "Exhaust Pipe B" is the expansion box. The cat has holes for sensors (maybe he just plugged them!).

Hi JockoT, I don't think "Pipe A" is a catalytic converter. It's just a pipe. The catalytic converter on the VS is bolted to the exhaust manifold vertically, and downstream of it is Pipe A. As you can see, Pipe B includes the resonator which is not a separate part, but welded in. I currently have a catalytic converter where the resonator should be in Pipe B. In non-VX/CX models, the catalytic is approximately between Pipe A and Pipe B. On the VX, there is no catalytic below the car, but in the engine bay bolted to the exhaust manifold.

I believe your statement that a cat normally has plugs for sensors is true. He didn't use them, as this would never work with my mechanic's configuration. Another poster in another forum where I cross-posted commented that the cat so far in the back will be useless as the exhaust is too cold, and also 2 cats in serial will cause too much back pressure among other things.

All that knowledge is the result of my research over the past 2 days, and it is more than I ever wanted to know about my car :) Please let me know if my summary is wrong.

VX has only one cat placed as close as physically possible to the exhaust ports in the cylinder head. Only replacement i am aware of is OE and big money. They are know for cracked manifolds (not the cat). Lots of US cars have to cats in the same exhaust stream (4 on dual exhausts) and they have two sensors with the second one checking the condition of the exhasut for OBD2 self diagnostics.

I owned a VX and worked on cars for 60 k hours (30 years). Mine was bought early in 2009 with 28.5k miles totalled and used by an insurance company for training for 14 years stored inside in a climate controlled environment.

I stand corrected. On my Jazz, Pipe A is the Cat, and is connected straight to the manifold.
https://www.hondafitjazz.com/manual/A...5601KBAD01.PNG

The more I kook into it I now see that some vehicles destined for California required two Cats in tandem. You learn something every day. Thanks for extending my boundaries. Even at 70 I still learn new things!

But not the Civic VX - or yes?