Hey guys, sorry i know you must h8 these questions, but in need of suggestions, so here goes

i have an 01 dc4 obdII. had it inspected and the mechanic reset the codes and passed it but then few hours later the check engine light came back on. i have a cheap high flow cat i bought online off amazon. The previous mechanic had said it was the rear 02 sensor near the cat, this recent one said it was the front sensor the rear was still good. So he replaced the front sensor and reset the rear 02 sensor after it said something alone the lines of "catalyst efficiency failure bank or something. After resetting it the same day it was gone for about an hour or two when it came back, i was driving in 4th at around 3krpm doing 75-80..

I had ordered the original honda rear 02 sensor which costed about 315 but did not use it. He had replaced the front one with a Denso which is the brand Honda uses yet it was about 100 cheaper then from Honda. I'm thinking if it's the aftermarket cat that's or maybe its the rear sensor needing replacement or that high flow cat just isnt doing its job. So any suggestions???

I was looking at this: http://www.amazon.com/gp/product/B00...A2XI3LTSB8UDVS
Supposedly there's a customer who used this one and passed the smog test.
The original Honda cat is about 630 from del ray acura, way too much for a cat.

I want to make this check engine light never come back, not spend too much money, and yet still have a nice exhaust note not too loud but that passes the test. Thanks

 

You could always just get a jumper harness and a OBD1 ECU and convert it to OBD1. That will do away with the rear O2 sensor.

 

I had a high flow cat and with it I got the 'efficency failure' code, but I fixed it for $25.

My secondary (rear) 02 sensor was seeing too much exhaust, when compared to the (front) primary 02 sensor.

I read a thread on this site that recommended that I go to e-bay and type 'angled 02'

I used the angled 02 adapter on my (rear) secondary 02 sensor. Just follow the written instructions.

I did not replace either of my oem 02 sensors.
My check engine light has not come back on, for 1 year.

I also read that I could stack 2 spark plug foulers, but I noticed that the wires on the 02 sensor would be stretched too tight and I did not want to extend them.

So, I spent $25. It is possible that my car might fail its next emissions, because they do a visual inspection of the exhaust system. In that case I will put the OEM cat back and get it passed.

 

What is the "P" code. It could be the sensor or could be the cat, post the code.

 

I'm pretty sure that all obd2 codes start with the letter P

 

Thank you, very helpful. I now know what the problem is. It's the cat, since its too high of a flow, the rear O2 sensor sees more exhaust fumes then the front one on the header. Does not affect engine performance at all. It's only an emissions issue. Nonetheless, seeing that blasted light bothers me. So a spacer/adapter was installed, sort of tricking the computer that there is a cat there doing its job. The light went away. I am going to do a test run and drive at lest 30mi at above 60 for at least an hour and see if it comes back. Hopefully it won't. If anything, the oem cat can be replaced just to pass the inspection. After, you can put your high flow/performance cat back on. With that blasted light surely coming back. Also the O2 sensors should be checked and replaced if needed. Thanks guys for your help. I learn a new thing about Honda and its motors everyday. Peace ya'll!!

Oh and I dont have the code, i just know its a "Catalyst efficiency failure" or something of the sort

 

A non fouler is the answer to your prayers.

 

dumb question, what is a fouler?

 

just go to autozone/pep boys, etc and ask for a spark plug nonfouler