You can also smell unburnt fuel/incomplete combustion any time any engine is started cold because catalytic converters, even those that are new, operate very inefficiently until they get some heat in them. What you're smelling may be a sign of absolutely nothing.
Instead of continuing to just throw parts at the car hoping to fix the problem, take it to a mechanic and have him diagnose and repair whatever's wrong. Not only will that cost less than replacing catalytic converters for no reason, it might also fix the problem.
Also, it's a bad idea to run the car with a failing O2 sensor because doing so long enough CAN actually ruin your catalytic converter(s), so I'd get it fixed not just ignore it until next year. Good luck.
I had the same problem some months ago!
Auto Zone said the code showed a defective sensor.
The engine ran perfect, so I decided to replace the air filter.
That fixed the problem.
The filter seemed to be oily.
Perhaps the oil was on the street or I happened to be following
an oil burning vehicle!
My Jimmy has 60,000 miles and still passes inspection!
Until you get the trouble codes, there could be a lot of things. If you want to start spending money about this problem, buy a little $50 code reader. It will pay for itself the first time you use it. The trouble codes tell what the problem is. Tighten up the gas cap. Hope that's all it is and if that fixes it, buy a lotto ticket too. Good luck.
I would spend the money on the sensors before the cats.
