Test pipes and spark plug none fouler

[freeon]

I installed some test pipe along with the spark plug none fouler for the o2 sensors. Every time I go out the cel comes on. The code is P0420(Rear Catalyst System Efficiency Below Threshold) What can I do to stop the light to come on.

 

[pingu81]

I have the same setup and my CEL still comes on too but after a period of driving it for a bit. Are you using the DIY non-foulers from NAPA? I switched to an 02 simulator from eBay which is longer and found that made the situation better but still not a complete fix.

 

[BD]

Did you stack two of them together?

 

[freeon]

Did you stack two of them together?

Yes

 

[spider2k]

did you drill out one or both of them?

 

[NSXRguy]

i have the same setup, but never had a problem with the CEL

i had 2 non foulers, but only drilled out the top piece. the bottom piece still had the smaller opening

 

[jlsnyderNSX]

I need to get off my a$$ and fix this problem too. I'm glad to know Napa sells non foulers.
Thanks, JL

 

[freeon]

did you drill out one or both of them?

Only drilled the top one

 

[peiserg]

there's a guy here on prime who sells an electronic non fouler plug.. supposedly 100pct success from what i've read. I used the 2 stacked non foulers and had success.

 

[ken sampson]

Hey I have test pipes but what are the plugs for?

 

[docjohn]

On my obd-2 96 when I used test pipes I just put the OE O2 sensors in the bungs on the teat pipes and only threw a cell when the heater unit went on one of the sensors.

 

[freeon]

I tried plug welding to hone in the adapters. Plug them half then 3/4 still getting cell. Anything else I can try. Could it be a bad 02 sensor

 

[pingu81]

Forgot to update this thread. My problem was that there was an open bung. Plugged it up and no CEL since.

 

[freeon]

What do you mean by an open bung

 

[pingu81]

My aftermarket headers (or test pipes, can't remember which one) came with extra 02 sensor bungs. One of the extra 2 didn't have a plug in it so it was letting air in/out therefore screwing with the reading being sent to the ECU.

 

[freeon]

I wonder what would happen if I was to plug weld the hole completely in the adapter. It shouldn't read any bad gas anymore and hopefully no more cel