P0420/0430 codes coming up more frequently
 

Hi All

I have been having issues with the 0420 code coming up every few months or so, and now I'm reasonably frequently getting both 420 and 430 coming up now. There have been no new mods done since I've had the car and the MAF was cleaned a couple years ago, so something appears to be failing.

Car and mods:
997.1 C2S 2005
EVOMS airbox with dry filter and sock.
Older fabspeed single (not x-pipe) cats, otherwise no other exhaust mods. Age? dunno but +5 yrs I guess.
ECU tune unknown.

The car is tracked reasonably often and serviced regularly.

I would say the aftermarket cats are starting to pack it in. They don't have nearly as long a life as the factory ones.

Do these codes do anything to the fueling or the power? My long term fuel trims are normally around -10.

time to get the mini cats less than 200 bucks

Well, both the codes continue to show. I note that during the CEL duration, both Short term fuel trims are -14. When I clear the 420/430 codes the trims immediately return to 0. Long term trims are now almost 0 all the time (unlike what I said above).

I find it unlikely that both fabspeed cats would fail at around the same time??

NO OTHER codes at all. post 02 waveforms look similar to pre 02 waveforms, indicating that the cats are indeed not functioning very well.

I think the cats would fail at the same time. They are the same manufacturer, the same age, the same usage, etc...

where/who??

Could it just be bad O2 sensors?

I had these codes when I got my 200 cell cats. Eventually put on O2 spacers and codes went away. The spacers are cheap. Mini cats achieve the same result. Don't have the link handy but just search online

Well, I got these spacers for the post O2 sensors and it seems my problem is vastly reduced. I haven't been on long enough drives to really evaluate it but a handful of shorter drives would normally bring up at least some pending codes. No codes even pending have been seen yet...

I believe the smaller hole at the bottom might be creating a deadspace next to the sensor that is giving it the lag in response time that the system is expecting.

Dead link

These would work just as well.

https://fastmodz.com/products/ippc-2...7fd46b15&_ss=r