Intermittent P0420 Check engine - Catalytic Converter replacement?

Fix the oil burning issue that is causing it to go bad and then try whatever snake oil in a bottle to revive your cat.

Spoiler alert: The Prius is built to CARB emissions standards. Putting in a Federal/EPA cat will eventually trigger the 420 again.

 

It takes the muffler guy about 30 minutes to weld in whatever you bring him realize it aftermarket catalytic converters are not going to have as much material inside of them that's what the factory deems necessary for the Prius so you may never get the light off or it may go off for a minute and be playing the games is playing with you now If you live in an emissions state then you have to deal with this I don't and I don't.

 

I would get a better cat that has worked for many. A Walker 16337.


There is no way to clean a clogged cat, especially on the car using an additive.

 

You can try it I've heard people swear by it I don't have emissions where I live so what's the least of my worries One of my cars has no catalyst in the whole plumbing system oh well funny thing when it's put on an exhaust gas analyzer it sniffs as clean as a new one or a new one of that year model It's in the spec I think that's pretty funny My old Corollas did the same in Massachusetts gut the catalytic converter put it back up in place. Take it in for the sniff test passes with flying colors thank you bye.

 

You are good to go I lived in Western Massachusetts during the years where I wouldn't have been good to go for sure or they had the tailpipe sniffer and all that nonsense late '70s early '80s and down here where I am we don't have emissions doesn't matter the year of the car in the county I live in so I don't have to do anything check engine light can be on they don't even care what the codes are they don't even look My car I get to honk the horns flop the turn signals and they might look at the tires and make sure there's no white light leaking from rear colored lamps and that's it so basically the same as you.

 

No chemical way to clean a cat on or off the car. Passing inspection is not the only reason to replace a cat. A clogged cat will keep the check engine light on which may hide another serious issue. A clogged cat can reduce performance and efficiency. A really bad cat can damage the engine. Some might remove a bad cat and straight pipe it for the last concerns but you would still have a check engine.

 

I've read some possibly-promising things about circulating a heated citric/oxalic acid solution through it off the car. Have had no occasion to try it, though.

Depends what's wrong with the cat, of course. It may reportedly help if the honeycomb surfaces are fouled, impeding the catalytic reaction. Doesn't help if the honeycomb is melted into a blob, impeding exhaust flow.

 

First things first. Ever replaced O2 sensors?

Replace downstream O2 sensor. It is screwed into the cat pipe under the passengers seat and comes up into the cab on the passengers side left kick panel. If that doesn't solve the problem replace the upstream. This one is a bch and you need the right socket. Try the downstream first though.

 

The code you have specifically tells you in the text as little of it as there is that the catalyst is below threshold not the O2 sensor not the muffler not the upstream sensor but the catalyst is below threshold somehow it's able to read that probably by the O2 sensor stuff and come up with that diagnosis My car has the same thing until I put the proper converter on it that light's going to stay on with a real crappy cat it might go off for a week or so and then come right back some people are saying that the Walker or whatever brand cat that's made specific for this application has done okay so that may be something to look into I don't have to look into any of it as we dumped our emissions testing where I live part of the reason I'm here

 

lol, that's a parts cannon approach. If it gives you p0420 then the sensor is working, waste of $$.

 

Depends. What scantool are you using?

Posted via the PriusChat mobile app.

 

There is a method to clean the catalytic converter and restore 85% of function however it requires citric acid and wood bleach oxcylic acid and it needs to be pumped through for 6 hours there is a Portuguese paper from a university floating around a 1mol mixture if you want to clean both you will need an empty oil drum, you'd be far better off cleaning yours than using a fed cat it will mess with your ECU settings the original cost like 2 grand plus to replace if you can get it. Mine was stolen before I could try...
Just a thought wood bleach and citric acid are cheap so is a thermometer a coil heater and a 12V pc cooling pump.
terramir

 

Yeah but is any of that nonsense cost it to your health while you're doing this cleaning business Is there a chemical reaction between the chemicals you're using and the converter itself? Maybe that's the reason people and places don't do such things? I don't know there's all kinds of different things that people have tried and may have gotten the light to go off long enough to get through inspection in Portugal you have emissions testing? I thought in lots of those countries that was the least of your problems? The below threshold catalytic converter doesn't cause you any running issues generally speaking My gas mileage is still what it was when the cat was in the car and all of that like 47.1. what will not be healthy to your converter as if your engine is burning oil and you're plugging up the converter with oil that'll get you all the codes and eventually it'll plug up the catalytic converter in the engine will run extremely poorly like it would on a normal ice engine catalytic car setup You see the catalytic converter glowing red or you may not see that in the Prius but the same thing is happening putting a straight pipe there eliminates all that If you add the stainless steel spacer with the little piece of catalyst material in it but little 90° thing and angle it right You may get the light to go out where I live I don't care about the light I just leave it on your place of residence may be different.

 

1 mol mix citric acid and wood bleach is from a chemical perspective kinda benign, it just clears the gunk out of the pores in the ceramic household bleach is more dangerous. The pool chemicals are even more dangerous. Otherwise I would have never mentioned it. You have to heat the acid or it wouldn't work that's how weak it is. As long as you read the paper and use universal precautions i.e gloves googles and don't stand over it a breathe it in its harmless. Even from an environmental perspective. Common sense goes a long way fear mongering might have a place but not when bleach is more dangerous.
The acid is just strong enough to clean the carbon deposits in the pores there is no way it can even etch those metals.
terramir

 

So then maybe you can just or maybe I can just take mine and have it tanked like they do things at the machine shop I don't know how they do things exactly in your country at this moment I'm not really worried about fear-mongering I am the least person to be involved in any of that I'll try to blow it up right here at my house no problem let's see I'm still here so there's always that but I was thinking maybe it could go to a metal fabrication shop where it can be tanked and you mentioned removing the carbon deposits out of the brick and what have you You know the Prius converter has more of that material that is precious that's in the catalytic converter itself whatever all that stuff is. The Prius has more of it it's denser whatever you want to call it and I guess over time that gets used up and sacrificial or something I don't know and then I guess when that happens it becomes below threshold I have seen where people have used cata clean and chemicals like that. And it's gotten the light off at least long enough to get through their emissions test but other than that I have no idea I know it's a big problem and there are some aftermarket catalyst now that's supposedly can do the job and put the light off so if that's what has to happen where you live there are some options I don't have any of these problems where I live so I don't work with them much anymore I'm going to see if putting the spacer in my non cat system in my '09 will get the light off and then that will be that.

 

His country is the USA so not sure why you've phrased it that way.