Has anyone tried the P0420/P0430 fix where you solder a capacitor and resistor into the downstream O2 sensor's wiring?

I get the codes due to HP Cats and free-flow exhaust.

I've read where this fix is great for say, 2000 and earlier OBD II systems, but might not work on more recent cars where the ECMs are more precisely tweaked.

I might try the mod this Friday or Saturday, but wanted to see if there were any success (or failure) stories out there.

Thanks!

 

Scardini, which cats are you running? I've got the Nameless Performance High-Flow 200-cell cats on my 1997, and they haven't tripped a single code in two years.


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I've heard of it, never tried it.

As I understand the idea, though, I'm not sure that 'fix' is the right word. I think it just tricks the system so as to mask a problem ....without fixing anything.

Cheers
DD

 

Hi guys,
Yes – I have the Nameless HP Cats. I also am the proud owner of a one-off Nameless SS FF exhaust system that they custom made for the car a few years ago.
A little history: The previous engine (130K miles) burned quite a bit of oil, yet despite this I rarely, if ever, got the 420/430 codes. That engine spun a couple bearings last year and was replaced with a 50K mile engine that runs beautifully. Oddly enough, after the swap, I started getting the codes as well as a B2S2 O2 sensor heater INOP warning. The O2 sensors were original (130K), so I replaced both lower ones with new, good quality Denso sensors. Now I get the 420/0430 codes at least every other time I drive the car, but she runs absolutely wonderfully. I even get best-in-class gas mileage (from what I’ve read).
I’ve heard that HP Cats and/or FF exhaust systems commonly cause these codes to appear. I’m sure the engine and emission systems are fine, so modifying the signal to the ECU/ECM with a “fix” isn’t ignoring a problem; it’s just making a nuisance alert go away. For just a few bucks, and some snipping and soldering, I figured “why not give this a shot”?
However, I’ve read that to successfully trick more recently engineered ECUs, you need an O2 sensor signal simulator that actually responds to the upstream sensor’s outputs. I believe these cost around 100 bucks a pop, so that’s not a realistic option. “And” it’s quite possible that the article I read on this was actually written just to promote sales of these devices (sneaky marketing!).
This is why I’m querying the brain trust here for more info. It would be nice to hear of someone with a 4.2 engine having some success with the capacitor & resistor mod.

Adios Y’awl!

 

Ive always had luck with the o2 extender type spacers (antifoul spark plug extenders). Both cats in my 2001 kia are actually removed and the spacer worked flawlessly. Ive done the same in several other vehicles in the past and it worked as well. Its worth a try as they are relatively cheap