P0420 or P0430, Catalyst Efficiency and cleaning catalytic converters.
One of the most frustrating engine codes in a vehicle is the infamous P0420 or 0430– both of which mean “Catalyst efficiency below threshold.” But what exactly does catalyst efficiency mean and can you clean a catalytic converter to get rid of the P0420 or P0430?
In this post, I’m going to explain what catalyst efficiency means, show you if it’s possible to clean your catalytic converter and introduce you to a couple options made for getting your vehicle to pass inspection with a P0420 or 0430 engine code.
Cataclean is the original “catalytic converter cleaner”
What does P0420 or P0430 mean?
In simple terms, a P0420 or 0430 engine code means that the catalytic converter is not “converting” as efficiently as the manufacturers specs. In order for the above statement to be simple, you have to first understand how a catalytic converter works.
Im going to (as) quickly (as possible), explain to you what a catalytic converter does.
How does a catalytic converter work?
Its important when trying to figure out if a catalytic converter can be cleaned to first understand how it works in the first place. The main point of a vehicle having a catalytic converter is to decrease harmful emissions by “converting” them into a safer gas before they are released into the environment. This is even more pertinent on a direct-injected engine where maintenance is even more important.
The way a catalytic converter achieves this is by forcing the hot exhaust from a cars engine over “catalysts” such as platinum, palladium and rhodium causing a chemical reaction that converts the fumes into gases that are safe(er) for the environment.
Over time, the catalysts that convert inside of a catalytic converter wear out and lose efficiency. When this happens, the engine can no longer produce safe gases– instead releasing carbon monoxide and other nasty chemicals into the environment. This is also when the P0420 and P0430 engine codes start to appear and prevent the vehicle from passing emissions tests.
What does “Catalyst Efficiency” mean?
Catalyst efficiency is as simple as it sounds. After the above explanation of how catalytic converters work, you should be able to understand that “catalyst efficiency” means the precious metals are no longer converting at an efficient enough rate. It’s a lot of big words to simply say that the catalytic converter isn’t doing its job anymore and needs attention.
If a P0420 means that the catalyst efficiency is below-threshold, one has to wonder how effective cleaning a catalytic converter could be. Can you increase the rate at which your cars catalytic converter “converts” by simply cleaning it? Or do you have to replace it/them in order to pass inspection?
Does cleaning a catalytic converter work?
- In recent years, several companies have started to market products that claim to clean catalytic converters and some even claim to be “emissions systems cleaners” altogether. If you understand how cars work and emissions specifically, you have to be skeptical when a product says it cleans catalytic converters or the entire emission system.
In order to validate these claims, I went on a research hunt to try to figure out how catalytic converter cleaning products work. Here’s what I found.
How catalytic converter cleaners “work”
The first time I ever heard about one of these products was “Cataclean” which claims to be the original catalytic converter cleaner. In the product description for Cataclean, it states that the product can decrease hydrocarbon emissions by 50%, cleans carbon out of the catalytic converter and also cleans the injectors and oxygen sensors.
When people buy Cataclean, it’s usually because they are trying to clear a P0420 or 0430 without the catalytic converter. Nowhere in the description or advertising for Cataclean does it claim to fix a catalyst efficiency code, which is smart on the part of the company. Instead the bottle of Cataclean (PN 12007) states that “if the catalytic converter needs to be cleaned, pour in a bottle to extend its life.”
The reason Cataclean says this is because cleaning a catalytic converter does not fix it and if the check engine light does go out, it’s likely to come back on in the future. This is because usually by the time the cat efficiency code comes on, the precious metals inside are depleted- not dirty.
Emissions System Cleaners work the same way.
In the same way that Cataclean works, emissions system cleaners are essentially just fuel system cleaners.
Although emission system cleaners are deceptively marketed as a way to pass inspection without fixing anything, there are many components that will put the check engine light on that can’t be fixed. Wiring problems also account for many of the issues that cause a check engine light and prevent inspection and those can’t be fixed with snake-oil. You need a probe tester and the knowledge to use one.
Cataclean doesn’t fix the converter, but it can prevent failure.
Cataclean will not fix your catalytic converter and despite the misleading name, the company behind it does not claim that it will. What Cataclean does do is prevent the failure of catalytic converters by keeping them clean of carbon, oil and raw fuel which are more often than not the cause of a bad catalytic converter.
One of the worst things for the health of a catalytic converter is a misfire. The reason a misfire will ruin an engines converter so quickly is because the cylinder no longer burns fuel from the injector, sending it “raw” into the exhaust system. Absent a misfire, cleaning a cars catalytic converter is actually a good idea in terms of routine maintenance.
If Cataclean won’t fix my catalytic converter and there’s no way to clean it, how can I get rid of a P0420 or 0430 without replacing the bad converter?
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How to get rid of P0420 and P0430 without replacing the converter?
The problem with buying a new catalytic converter is the price of a new one. Compounding that problem is the issue of aftermarket converters being banned in many states and ineffective overall in most cases. So, how can you get rid of a P0420 or P0430 code without buying a new catalytic converter?
One way to pass inspection without replacing a bad converter I learned a long time ago was to trick the oxygen sensors into thinking the exhaust was cleaner than it actually was. How can you “trick” an oxygen sensor?
In many (not all) cases, you can get a vehicle with a bad catalytic converter to pass inspection with two spark plug non-foulers, costing less than $10 total and a little bit of labor.
How to pass inspection with a spark plug non-fouler.
An effective way that I’ve found to pass inspection with a bad converter is to use the spark plug non-fouler trick. In this procedure, you do the following to trick the ECM,
- Drill a hole in one non-fouler with a 1/2” drill bit.
- Screw the two non-foulest together.
- Remove the rear (downstream) oxygen sensor from the exhaust on the affected bank.
- Screw the non-fouler into the exhaust.
- Screw the oxygen sensor into the spark plug non-foulers.
- Clear the check engine light, drive the OBD cycle, hope the light stays off.
For sure this isn’t a 100% thing and far from an exact science. It’s also illegal in probably all fifty states, so don’t try it where smog inspections are present. I have seen it work more times than anything else though to pass inspection with a bad catalytic converter.
Also Read- How to Properly Maintain a GDI Engine in 2023
It’s likely you need to buy a catalytic converter.
It’s a good chance that you will have to end up buying a new catalytic converter even if any of these tricks are successful. None of them are a sure thing and none of them are a permanent way to fix your converter without replacing it. It’s likely you’re going to have to remove the exhaust and hangers to replace the catalytic converter.
If you can’t afford an OEM catalytic converter, there are some aftermarkets that are better than others. I have had good luck with the catalytic converters I’ve bought from FinditParts online and they are going to be far away and the cheapest place to buy a non-OEM or even a universal catalytic converter. There is a valid case to be made for OEM versus aftermarket catalytic converters, but there are exceptions.
Although I always recommend buying OEM catalytic converters, I also understand that they are crazy expensive and sometimes the car isn’t worth putting thousands into or you may not plan on keeping it long. In these cases, I see no problem buying a universal or aftermarket.
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