I did a search and nothing useful came up.

I swapped the stock cat out for this generic high flow cat. It's throwing a P420 Catalytic Converter Inefficient which makes sense because the computer expects emissions results data with the stock cat.

I'm just wondering if anyone knows a way around the P420 CEL to make it accept the fact that it doesn't have the stock cat anymore.

Thanks.

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have you tried resetting the ecu by disconnecting the battery and then letting the car idle for 10 minutes like you do when you change the intake on a car?

 

Most "high flow" converters have larger holes in the honeycomb material in order to be high flow.
Usually this means that the cat will burn less fuel and the rear O2 will notice this.

That's why you get the code and most likely you won't be able to get rid of it.

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Yeah that's what I figured.

I did reset the ECU by the way.

The burning less fuel would explain the random backfires that go "pop" sometimes if I gas it up all of a sudden, instead of a gradual acceleration...

 

xB error Code P420 Help!!!
I need a OEM or Stock Catalytic Converter for my 05 xB. I've tried the Magnaflow cat and the VSC, Trac Off and Check Engine light are still on.
Apparently there isn't enough platinum in the Magnaflow to fully keep the lights from returning and correcting the problem.

I'm in VA and need to pass Emissions.

Any suggestions?

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You could always wire in a resistor to the rear O2 sensor... its what you do if you delete the cat and don't want to deal with lights.

I still can't find the actual ohm value we 1NZ-FE guys need though. Anybody know that one?

 

this is what i would like to know after a long search got it here thanks for the info need more stuff.

 

Hi, Last week the engine oil STP (5-30W full synthetic), was changed. The air filter was replace. Scion xB 2004, it is getting old. Was found the failing Code P420, and P420P. After changing the oil was the computer reset.
Fuel injector cleaner was use for the first gas tank. Then after driving 350 Miles on the Highway, the failing code P420 Bank 1, reappear. Must be the spark plugs by the end of their life? Or the Mass Air flow Meter MAF sensor ?
The 3 x Red lights (Check Engine/VSC/Traction) are ON. Skoty Kilmer say to ad one gallon of paint thinner to the gas tank and keep driving to clean the catalytic converter.
If will be use the high gas octane 95 instead of 87, this change in gas quality, will be better?

Please let me know if the winter is coming, should the engine will have 5-20W Mobil One for High Mileage engines (the car have 177k Miles)? Will give a better start on cold frizzing arctic days?



If will be used a 1.1 Kilo Ohm resistor/0.25 Watts, in parallel with those Oxygen sensors, can one adjust the uncomfortable failure code P 420 Bank 1? To pass the State Inspection?

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Illegal and also won't work.

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it does have a check engine light on; it's catalyst inefficiency. I know from experience over the years that's a new catalytic converter no questions asked. You will never be able to trick it or fool it you just have to replace the cat