> Had you driven any length of time with the MIL on? That can be enough to
> finish off a catalytic converter which is past its best. Freeway driving
> for any length of time, especially every day, should be enough to burn off
> any contamination and keep a cat in good shape - your mileage seems early
> to me for it to fail based on your driving habits. Is the engine getting
> up to full operating temp and giving good heat?... IOW no sign that the
> thermostat might need replaced.

First of all, thanks for all the comments from everyone. I appreciate it.

To sort of address what everyone has asked, here's the background that I
left out of the original post to keep it from becoming too convoluted: (Just
in case you are interested).

A few months back (which adds up to quite a bit of mileage on my car
quickly), a gas pump did not click off, and before I could stop it, the tank
had filled and the gas ran out onto the ground. The MIL came on with the
P0420 code. From that day forward, pumping until first "click" resulted in
the P0420 code. So in the repair interim, I started filling up with less
fuel than I believed would fill the tank. The MIL would go off after a few
trips.

The problem was that now my fuel gauge was no longer accurate! It remains
that way to date. I'm guessing it's 3/8 to 1/2 of a tank off! (Showing
emptier than actuality).

Recently, the MIL came on again, this time permanently. The code I received
was the EVAP leak -- I bought a new Honda gas cap to test. Almost right
after that, I received the P0401, EGR insufficient flow. This is when I
took it to Honda to have the free port cleaning -- solving the EGR flow
code.

Gas mileage seems okay. When new, I think I was getting around the 28MPG as
advertised. Now when I check (meaning I have to resort to letting the gas
pump click once), it ranges around 26.5-27MPG, 25.5-26MPG w/ A/C on some
days. I think the worst is around 25MPG. I did have the thermostat
replaced a few months back (probably time again). I wasn't sure, but before
the replacement, it did seem like the engine was running too cold even for
the winter...dragging down the MPG.

I just received my Helm manuals today, so I'm going to look into checking
the Fuel Sending Unit, as well as the other emissions/re-circulation
components such as the PCV.

The reason I was skeptical about the Catalytic converter was that there was
so many other issues going on with the emissions system. But from reading
the comments, it seems like that very well could have pushed the converter
over the edge.

If you have any more suggestions, feel free to send them my way.

Thanks.