This has car been outstanding. It now has 184000 miles and I would like to pass it on to my kid

The CEL code for the catalytic converter P420 has been in for last 6 months but the car continued to drive great until this morning when the fixed CEL code started to blink.

I pulled the following codes from my scanner:
P420,P0172,P0175 P0301, P0303,P0306 P0300

any thoughts on troubleshooting?

 

Need to fix "too rich" codes first. By looking at the miles car might need valve adjustment.

 

Could the too rich codes be related to poor gasoline?

 

Doubt it. Had couple Odysseys that threw too rich codes with >150k miles and valve adjustment cured them. Exhaust valves are too tights and not close all the way.

If that is the problem, leave it long enough, and it will burn the valve and lose compression.

 

New coils (Hitachi) and plugs installed;CEL is now off. Engine runs great