96 integra. has had a eng warn. light on for 80,000. i check the codes now and then it is for #2 o2 sensor or cat. not working. I dont need a cat where i live. would love to make this lite stay out. understand a little bout how it works a comparision between the two sensors. how do i fix or trick this annoying problem. previous owner had just installed two new sensors and it still doin it. thanks

 

oh well i said **** it. got a jdm ecu which only needs one sensor. problem solved

 

I had the same situation with my 02 Civic SI. What i did resolved the issue so I would like to share.

I used GUM-Out Fuel system cleaner, Fuel treatment and octane booster. I don't think the Octane booster was from gumout. I did this 3 times with my 3 fill-ups using 93 octane each time. The check engine light came on and after 150 miles, it shut off. Then it came on again after 110 miles, and then shut off after 80 miles. It came on one more time after 300 miles and shut off after 29 miles. It hasn't come on since. It's been 950 miles.
The best part is my car is running like it's never run before. It has 122K and the horsepower is unbelievable and it is silent!
I treated the gas 3 times in a row. My mechanic said the Hondas are famous for CAT codes and what I did cleaned the sensors. I can't say enough how good the car runs, sounds and moves now!