I've talked about this before but thought I'd see what you guys think about it now that I've got a deadline of March 31 to get it figured out. The Check Engine light is on in the '98 Accord. In the past, it's been intermittent and I could delete the code with my cheapo scanner and have it stay off long enough after a few drive cycles that I could get it to pass emissions. That is no longer the case. The code that comes up on the scanner is "Catalyst Below Threshhold - Left Bank" This is a 4cyl so there's only 1 bank. The code number for OBDII is P0420. I've searched on the internet and get conflicting advice wherever I look. Some say that I should replace the 02 sensors. Others say this generation Accord is know to have CC that fail earlier than you would expect. The car has 135K on it. The OEM sensors will be about $225. The OEM CC is $510. Either way, they aren't parts I just want to throw at the problem and hope it works. On the most basic level, the second sensor is not seeing whatever it needs to see in order to be within spec. That could be a bad downstream sensor not reading the correct differential. That could be the upstream sensor not reporting correctly. And it could be that the CC is not doing its job correctly, or some combination of the three.What are people's experiences with non-OEM O2 sensors as well as non-OEM Catalytic Converters? Do any brands seem to be better than most?