I have a 2010 Honda Accord EXL with the V6 engine with 146k miles on it currently. I bought it used with 95k miles on it and had the timing belt, water pump and spark plugs replaced. I developed a misfire at 110k miles and at the time I was not aware of the misfire lawsuit and the Honda dealership failed to notify me about that. Well at this point I'm out of the lawsuit warranty coverage so I'm unable to get the rings replaced. Thankfully it seems as though the only cylinder that has any issues is cylinder #3, so at this point I routinely check the oil levels and if I'm going on any sort of long journey I pull the spark plug on that cylinder to make sure it's good shape. I've now developed a code p0420 I'm sure as a result of the misfiring. I'm not looking to pour in a $1000 for a new converter and I'm unsure if an a new o2 sensor would resolve the problem as well.
My question for you know that are more mechanically inclined than myself is should I look to trade in the car do what I've been doing and periodically check the plugs and maintain oil levels?
It's a very clean car and I've had no problems with it outside of the above mentioned problems, however I don't have any idea of the long term consequences of having these problems outside of poor fuel consumption and reduced power.

I appreciate any tips or advice on that matter.

 

The P0420 is likely due to excessive oil contamination of the converter due to the piston ring issue. Changing sensors generally will not resolve P0420 on later generation Hondas.