...oopsie
I decided to take it to a local shop and had them just cut out the flex section and replace with a universal flex section. Approx $150. 1 Hour to do. ....But, still had some exhaust leak noise. They found another leak. They removed the heat shield and noticed a small area of carbon build up coming from the exhaust manifold gasket.
I got home and started taking a closer look. Two of the manifold to block studs are broken! I ordered the gasket from rockauto and what I thought were the right studs/nuts. Nope.
Quest continues. (Trying to eventually rid this P0420. Hopefully not the CAT. I need to get rid of these exhaust leaks first)

 

I'm asking that same question. the california fit pipe is cheaper than the federal emission pipe on ebay. they say the california pipe doesn't have a bung for the o2 sensor, anyone knows of that to be true

 

My F23a1 has the O2 sensor in the manifold. This is a federal emissions car built in Japan. I replaced the head pipe with 1 from a co. on e-bay that's located in Canada for 75 shipped. Mine was the flat plate style of gasket (came with the pipe).
My old pipe had been welded on too many times, which is why I replaced the head pipe (someone had even welded the replacement cat to it). I ended up replacing the entire exhaust from the manifold back. I bolted on a Magnaflow cat, and a stainless steel Magnaflow cat back exhaust. Love the sound of the car, and living in the salt belt, the exhaust should last a little longer.

 

Pipe wrench:
What year/model/engine is yours? I'm pretty sure that all 3 of the engines available on the 1998 USA Accord 4-door had the primary O2 sensor located in the exhaust manifold. Not in the A-pipe. So none of the A-pipes should have a bung for the sensor.

The ULEV engine has a different exhaust manifold, and the sensor itself is very different. But the sensor is still located in the manifold.

 

I have a 2002 F23A1 2.3L V-TEC 4cyl. engine. My o2 sensor looks to be in the pipe from the manifold, if i'm not overlooking it?

 

In the manifold according to this...

 

Yours is probably just a regular "49 state" LEV car/engine. It should have a single outlet manifold, and use a flat gasket with 3 bolt holes in it. Look on e-bay for one, as that's what I did. In fact the last time I looked, the guy I got mine from was still selling them for 75 bucks.

 

mine is in the manifold. I would like to replace it one day. Thanks, I'll look into it.

 

Conceptually it's very easy to replace. Unplug the wire, unscrew the sensor.

In real life, it's usually stuck from heat & corrosion, so it's difficult to get it loose. PB Blaster or Kroil or something like that to soak for hours, then smooth torque with a long-handle wrench. Special "sensor-socket" helps because you can feed the wire through the socket.

 

I will do that.
Thank you