The first catalytic converters were developed in the 1970s and were installed on vehicles in the United States in 1975. They contain a catalyst, a material that helps convert the toxic emissions into less-toxic substances.
The catalyst is usually made of platinum or palladium. Over time cat converters have become more efficient. The newer converters can convert a higher percentage of the toxic emissions into less-toxic substances.
The converter clogs over time as your engine produces deposits from burning oil and fuel. As these deposits accumulate, they can restrict airflow through the converter, causing a loss of performance and fuel economy. Cleaning is therefore required to ensure that the units work optimally.
But the big question is, can a catalytic converter unclog itself?
In layman’s language, a catalytic converter cannot clean itself without your help. It will only unclog itself when it’s heated up. To achieve this, you will need to drive your car at higher revs, ideally 4000-6000 RPM, for about 30 minutes.
Why Catalytic Converters Get Clogged
Coolant or antifreeze combined with engine oil leads to sludge accumulation, which blocks the cat converter.
- Rust, dust, and dirt debris block the car exhaust system.
- A defective oxygen sensor can make the car’s computer system cut power and operate inefficiently, leading to increased emissions, which may cause your cat to become clogged. It is recommended to have your mechanic inspect your oxygen sensor constantly. In the event of an oxygen sensor malfunction, the mechanic should be able to rectify this problem
- Long-term usage of the fifth gear might result in the formation of carbon deposits on the converter. These carbon deposits produce soot, which clogs the catalytic converter.
- Leaking water into the engine causing it to mix with the engine oil owing to defective gaskets or seals. This creates rust and contaminant particles in the water, causing sludge buildup, which can contribute to catalytic converter blockage.
- Poor-quality fuel containing high sulfur contents also contributes to catalytic converter clogging. Use gasoline with a low sulfur content if you wish to avoid this.
Signs of a Clogged Catalytic Converter
A clogged catalytic converter can cause a drop in engine performance, as well as an increase in fuel consumption and exhaust emissions. Several signs may indicate your catalytic converter is beginning to fail or has already failed.
If you notice one of these signs, your catalytic converter may be beginning to fail:
Oxygen, fuel, and a spark are required for combustion in the engine. After each stroke, the engine draws in additional fuel and air into the cylinder for the next stroke.
Most likely, if the catalytic converter is malfunctioning, it could be partially or fully clogged.
Whenever this occurs, the toxic gases that are often released by the exhaust return to the cylinder.
When the engine “draws in additional fuel, it also expels these toxic fumes, which deprives it of one of the vital ingredients for combustion, mainly oxygen.
If there is no enough oxygen in the engine cylinder to support the combustion process, it will misfire.
When it is found that there was a misfire after scanning the code, you should examine the catalytic converter as one of the potential causes of the misfire.
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Poor Fuel Economy
The clogged cat converter causes reduced airflow, which causes the engine to consume more fuel than usual and results in poor acceleration. When exhaust flow is low, you are forced to press the gas pedal harder since acceleration is compromised. This causes the engine to inject more gasoline, resulting in an excessively rich fuel mixture.
A faulty catalytic converter inhibits the engine from receiving the required amount of oxygen. Less oxygen in the engine causes the engine to work harder, increasing fuel consumption. This indicates that the car will go fewer miles per gallon than usual.
Therefore, a drop in gas mileage that cannot be explained indicates an issue with your car’s catalytic converter. However, this does not necessarily mean that the converter has to be replaced, as a simple clog can cause the problem. However, replacement may be needed if paired with any of the additional signs.
Rotten Egg Smell
Well, there are no eggs hidden in the catalytic converter, but a rotten egg smell indicates a failing cat converter. The smell is often a result of sulfur gas.
Even while the odor is commonly linked with rotting eggs, some people describe the smell as similar to that of an open sewer. It is unpleasant to smell and might indicate exhaust fumes leaking into your car.
If this is the case, you have more issues than a nasty smell.
Since exhaust fumes include carbon monoxide, you must immediately get off the road if you detect a smell of exhaust smoke in your car cabin while driving.
Carbon Monoxide can induce unconsciousness fast.
A defective catalytic converter causes a rotten egg odor. The converter’s job is to convert the toxic pollutants produced by your engine’s combustion process into harmless emissions.
If this process fails, you will be able to smell the exhaust coming directly from the engine. Your car will also fail emissions check; if the check engine light is not already illuminated, it will soon be.
Can a Catalytic Converter Unclog Itself?
Typically, a cat that is clogged cannot unclog itself. The only way a catalytic converter may occasionally unclog itself is by driving at a specific RPM level for a length of time.
However, if you decide to help it clean itself, you need to find a highway that allows you to drive uninterrupted. Ensure you maintain 2500-6000 RPMs for at least 30 minutes.
How to Spot Cat Converter Clogs?
The first step in cleaning the cat converter is determining whether clogged or not to begin with.
Even to the normal person, a blocked catalytic converter reveals a handful of unique signs
Among the things you should keep a watch out for are the following:
- Hard engine starts.
- Car stall for no apparent reason
- Poor fuel efficiency
- Poor acceleration, even with the entire foot on the floor.
- Constant emission of dark gray/ black smoke from the exhaust.
- A rattling noise (not engine-related and is difficult to identify the source
How to Unclog Catalytic Converter? (Without Removing)
The first approach of cleaning a clogged converter does not need removal. This approach also cleans the oxygen sensors, fuel system, and exhaust system.
Simply tap the converter using a hammer to confirm whether this method is right for you. Strike it to make it vibrate, but not hard enough to damage or damage it.
If you hear rattling inside the converter, there may be broken parts/ sediments that can only be remedied by dismantling and cleaning.
If you do not hear any unusual sounds, continue with the following steps:
Get some high-quality catalytic converter cleaner. Some cleaners are designed solely for gasoline or diesel engines, and others work perfectly for both.
Add the cleaner to the gasoline tank. On the cleaner’s label will be detailed instructions on the amount to pour and the amount of gasoline that should be in the vehicle.
Go for a drive. After adding the cat cleaner, it’s time to take your car for a drive. The cleaner will be circulated while driving to clean the exhaust system. The cleaner’s label will provide the recommended driving time for the best results.
To get the cat converter heated enough to burn away any blockages and residue, experts recommend driving with an RPM greater than 3000.
If you drive an auto, simply switch to the “Sport” mode, as this increases the revs without having to increase the speed. Manual transmissions simply hold each gear for a little longer before shifting.
Observe the temperature gauge to prevent your car from overheating. If the cleaning procedure is successful, there will be less exhaust smoke, faster acceleration, and fewer engine misfires.
- Automotive degreaser
- A container for soaking the converter
- Floor jack penetrating oil, e.g., B’laster or WD-40
- Jack stands
- A wrench that fits the bolts on the converter Pressure washer Oxygen sensor spanners
Once you have all the necessary materials, follow these steps:
Before beginning, allow the exhaust system of the car to cool down.
Use the floor jack to raise the vehicle for you to access under without difficulty. Using the oxygen sensor wrench, remove the oxygen sensor(s).
Locate the converter and add penetrating oil to the bolts to loosen them. If it is welded to or connected to the turbo, it should be cleaned by a qualified mechanic.
After removing the bolts, remove and check the converter. A catalytic converter must be replaced if it makes a loud rattling noise when shaken, indicating that its internal parts are broken.
If there is little to no rattling, clean the body and wash its inside with low pressure.
After pressure cleaning, the inlet and exit pipes pour hot water & degreaser into the large soaking container.
Soak the converter for no longer than one hour in the mixture of hot water and the degreaser.
After soaking, rinse it with a low-pressure pressure washer, then allow it to drain until it is dry.
After the system has dried, replace it along with the oxygen sensor (s). Then, test the car’s performance by driving it.
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Using Baking Soda and Vinegar
This is the most affordable method of catalytic converter repair. Utilize the following method:
Pour approximately half gallon of water into an empty gallon-sized milk jug. Add one-half cup of white distilled vinegar and baking soda. Shake it up till it fizzes
Place the jug on top of the converter and submerge it entirely in the liquid beneath the automobile.
The resulting acidic mixture will dissolve blockages produced by antifreeze leaks or oil, making it easier to remove when you visit an auto shop for service.
You can also use this technique to remove stains produced by antifreeze leaks underneath your vehicle, but you should never mix ammonia and vinegar. When combined, the substances emit toxic vapors to humans and animals.
Hi I’m Marshall based in 1478 Doctors Drive Santa Monica, CA. I’m your DIY Car Repairman with more than 5 years experience in automobile repair, a skill I learned from my old man.
I started this blog to share my experience on both simple and technical aspects of your car.