"Catalyst System Efficiency Below Threshold "

Had ektuner39 on the forum ran his scanner for me and this code pulled up. The code says :

1. 3 way Cat Converter
2. Secondary o2 sensor
3. Exhaust system leakage

I believe it's one of the possible 3 above that is causing my CEL to come on. We reset the light after the scan and it came back on a week later. Should I just go ahead and replace the secondary o2 sensory ? If it's the cat , shouldn't I be getting bad gas mileage ? I still average 300 miles to the tank with the light on. Thanks any help would be nice.

 

BUMP

 

Is the cat stock?

 

Yes and everything else.

 

I will check alldata at work, its a common code for nissans but a honda application may be a different fault. Usually a cat code is due to the secondary o2 sensor (post cat) verifying the cat isnt functioning properly.

 

Bump.

 

Looked it up, you either have an exhaust leak or your cat is inefficient. Process of elimination but if you havent touched the exhaust system id say you dont have a leak, cat is probably bad... odd.

 

Guess I'll go ahead and order a new cat and o2 sensors. Thanks ForceFed

 

No problem.

Your o2's are more than likely ok, they can test them if you dont have the means to do so using a scope. Your cat sounds like its the cause.

 

What the... My CEL went away tonight. It was still on when I went to the gym...2 hours later , went to my car , started her up and behold... No CEL ! Now I'm confused.

 

A code will clear itself if it falls within the drive cycle criteria, meaning if the car acts a certain way for an alotted period of time the code will clear. Doesnt mean the problem went away, just that it was corrected for that trip. That should be a two trip code.

 

Sigh...Back up again... Replaced both front & rear O2 sensor , catalytic converter ( magnaflow oem spec CA OBDII approved ).. What is left ?

 

Ill look into it tomoro when i get to work. Seems odd that it would return. How does the car run itself?

 

The car itself runs fine.. I drive 80 miles a day to work and back home.

 

Im assuming you have already checked for exhaust leaks, or would have heard one.