I have a 1999 accord, that has no cat on it. The guy I got it from cut it out and took out the O2 sensor after the cat. I now have the fault code P0414. I was wondering if there is a way to bypass this so I don’t have a check engine light.

 

Does the test pipe he installed have an O2 bung in it? If not you will have to add one, or buy a test pipe that has one installed.

Only way to bypass it is to install the secondary O2 sensor in a spark plug de-fouler bung. If your exhaust doesn't have a bung for the secondary O2 you will have to add one, at that point you could actually add one that is longer than stock. This pulls the secondary O2 out of the direct line of O2 gases and will read normal and satisfy the ECU/ this will usually clear the P0414.

 

As suggested above, the least expensive way to try and solve this is to install what's called a mechanical O2 bypass. You build this using a $5 item called a spark plug defouler. You will need to drill a hole to install this.
Info and pics on what to get are here:
https://www.s2ki.com/forums/s2000-un...ulator-229959/

However, if you can't do this yourself, or don't want to, it might almost be the same cost (if you include labor) to just throw a cat back on there. If you can do this yourself, it's an inexpensive fix.

 

Thanks for the help!