Catalyst System Efficiency Below Threshold (Bank 1)

[whivins]

I had this trigger my "service engine soon" light. Anyone else delt with this? What will fix it? Thanks in advance for any help.

[blackmax23]

Yes, I have been getting the same codes, but in bank 2. I have a high-flow cat so I think that's my problem, but still not sure because the light will go off for a couple hundred miles, then come back on for another couple hundred. Goes through a crazy cycle like that...which is a pain in the rear with NY inspection! What year is your max?

[asianstyle]

had this problem awhile back when I first got the car, bought a y-pipe and high flow cat b/c it was cheaper than the dealership replacing the catalytic converters and also will benefit you with gains in hp. SES went away.

[whivins]

Sorry, I should have included it's an '01 Maxima. The O2 sensor was replaced about 5K ago. That's the only other trouble that I have had with the car. Thanks for your input.

[Mike G]

Mine does this when running the low octane/cheap fuel. I put in a bottle of octane boost and it generally clears out after a few trips.--Mike