A catalytic converter is part of your vehicle's exhaust system which plays a crucial role in removing toxic gases like carbon monoxide, nitrogen oxides and hydrocarbons from your exhaust. When you start your vehicle and your engine begins to burn gasoline, these toxic substances are a by-product that then filters through your exhaust system. When they reach your catalytic converter, the gas is passed across a honeycomb sort of filter that is made from what is called a catalyst. The catalyst in your catalytic converter is a precious metal such as rhodium, palladium, or platinum. When the temperature is high enough, around 800 degrees Fahrenheit and higher, the toxic chemicals in your exhaust undergo a chemical reaction when they reach the catalyst in your converter. That causes them to break down into less harmful substances, in this case things like carbon dioxide, water, and oxygen.
Signs and Symptoms of a Bad Catalytic Converter
It is often difficult to notice problems with a catalytic converter since it is part of your car's exhaust system and, technically, your car could function perfectly fine without the converter installed at all. However, it's a key part of your vehicle's exhaust and also helps drastically reduce the amount of dangerous pollutants in our atmosphere. For that reason, you should be on the lookout for the signs and symptoms when something is going wrong with your catalytic converter.
Noises: That honeycomb we mentioned that exists in your converter can potentially break apart over time. The honeycomb is made of the precious metal and ceramic and the pieces of it can break off. When they do, they're going to rattle around inside of your catalytic converter in a way that sounds not unlike a can full of rocks. The more pieces that break off, the louder it's going to get. You will be plagued by an incessant rattling sound every time you drive until you get it fixed.
Bad Gas Mileage: If your catalytic converter is clogged because there's too much build-up that's going to prevent your exhaust from filtering through it properly. When your exhaust can't filter through your catalytic converter it backs up into your engine. This can throw off the operating temperature of your engine and it will also contaminate the fuel and air ratio that gets in your combustion chamber. The result is your gas mileage is going to decrease and you're going to find that you're heading into the pumps to fill up more often.
Bad Smell: Since it's your catalytic converter's job to filter out various toxic chemicals from your exhaust, when it's no longer able to do this you're going to be noticing the smell of those unfiltered chemicals coming from your exhaust. The most noticeable one of these is going to be the sulphur smell that is produced by a gas called hydrogen sulfide. Hydrogen sulfide is a normal by-product of burning gasoline and your catalytic converter will convert it into sulphur dioxide when it's working properly. When it is no longer able to perform that function the unfiltered hydrogen sulfide will be released from your exhaust and it brings with it a smell that is reminiscent of rotten eggs. Along with the smell, the exhaust itself will have a darker color and will appear like grey or black smoke.
Poor Engine Performance: When your catalytic converter is clogged then your ability to accelerate is going to decrease noticeably in your vehicle. This is because your flow of exhaust has been blocked and it is backing up into your engine. You can consider it like your engine is being choked out because the fumes are limiting your engine's ability to properly burn the oxygen and fuel mixture and achieve its peak performance.
Failed Emissions Test: If you live in a state that requires you to take an emissions test and your catalytic converter is not functioning properly, you're going to fail that test pretty quickly. Every car is required to have a functional catalytic converter so if you have to take an emissions test and your converter is not working, they're going to require you to get it repaired. If you continue to drive with a malfunctioning catalytic converter you can be subject to some pretty steep fines as well. And you'll still have to repair it on top of that, so you're going to end up costing yourself many thousands of dollars.
Check Engine Light: Although a check engine light is very vague and won't offer you much indication about why it came on in the first place, if you're experiencing any of these other symptoms at the same time then it's a good indication you're having a problem with your catalytic converter and that's why the light came on. In this case it would have been the oxygen sensor that tripped your check engine light in the first place because the oxygen sensor is there to measure your catalytic converter’s efficiency. It monitors the gas levels in the converter and if it's not working properly the sensor is going to detect that the gases aren't being properly catalyzed.
When you get a check engine light on your dashboard and you're not sure of the cause one of the best things you can do for yourself is use an OBD2 scanner to find out what set it off in the first place. These are the diagnostic tools that professional mechanics will use to figure out why a check engine light is on your dashboard. Although the versions that they use are likely pretty expensive, you can get a functional OBD2 scanner for yourself from a site like Amazon.com for probably around $30 or so. This won't have all the bells and whistles of a professional OBD2 scanner, but it will give you the code for the specific error that causes your light to go off which can help narrow down the problem and save you time in figuring out what you're going to do about it.
Can You Drive a Car with a Bad Catalytic Converter?
If your catalytic converter were to fail on you, you could still drive your vehicle. In many ways this depends on how your catalytic converter failed. If it clogs, then that's going to cause your exhaust gases to back up into your engine as we mentioned. Over a long enough period of time this will actually stop your car from functioning so technically you would not be able to drive any longer. However, if the problem with the converter is that the catalyst material has broken off inside, or the converter has been removed, your vehicle will still function without it. It's not a crucial part for the performance of your vehicle.
That said, as we mentioned, driving with a bad catalytic converter or with no catalytic converter means you're going to be releasing a greater number of toxins into the environment. And you're also going to be subject to fines if you get caught driving without the catalytic converter as well. These fines can vary from location to location but are generally several hundred dollars. If you specifically remove your catalytic converter the fines can stretch into the thousands of dollars.
Why Do People Steal Catalytic Converters?
Believe it or not, one of the most unusual problems that some drivers have with catalytic converters is the fact that other people try to steal them. Because the catalytic converter is part of your exhaust system it can be accessed without actually breaking into the vehicle itself. But the reason thieves want it specifically is because of the metals that are used as the actual catalyst which gives the part its name. Catalytic converters are typically made with very rare and precious metals like palladium, rhodium, and platinum. If you were to collect enough catalytic converters you could make some decent money from a scrap yard off of them. A catalytic converter could pull in around $200 at a scrap yard.
If you head to AutoZone you can see the cost of new catalytic converters ranges from $300 to as much as $1,700 for some of them. The temptation for thieves to snag these off of a car is higher than you might think as a result.
Catalytic Converter Repair Cost
As we just covered, the cost of buying a new catalytic converter can be remarkably steep. It really depends on the make and model of your vehicle. When you need to have your catalytic converter replaced, the bulk of what you're paying for is the part itself. When you factor in labour you can expect to pay anywhere from $500 to over $2,000 to have your catalytic converter replaced. The labour is not typically that intensive for this job and might only cost you between $75 and $150 depending on the mechanic you take it to.
How to Clean Your Catalytic Converter
Given that your catalytic converter is such an expensive part of your car, you may be tempted to find a way to fix it without having to replace it. Luckily, while some parts of your vehicle only have the option of replacement, your catalytic converter may be able to be fixed with a simple clean up job.
What many drivers don't realize about the catalytic converter is that it's designed to work at extremely high temperatures. That means you need to push your car to get the most out of your catalytic converter. Anyone who does a regular commute down the highway or does a lot of driving outside of the city probably doesn't need to worry about this, but if you only drive your car in town then you could be putting your catalytic converter at greater risk. If you don't ever get your vehicle up to speed, you're not pushing your engine as hard as it can get, which means you're not allowing your catalytic converter to reach its optimal operating temperatures between 800 degrees Fahrenheit and about 1,800 degrees Fahrenheit. If your converter is unable to reach those temperatures, it can fail on you prematurely.
One way to fix this is to ensure that your catalytic converter is able to reach those temperatures. That means you periodically push your car to its limits on the highway. Take your car out of town and get up to highway speeds allowing your engine and the catalytic converter to reach their optimal operating temperatures. That's going to burn off a lot of buildup in your converter which will let it continue functioning properly for a longer period of time. It will effectively remove much of the build up that has accumulated along the intake, the cylinder heads, oxygen sensors, all through your engine and your catalytic converter. Do this perhaps once or twice a month, and your catalytic converter will last quite a bit longer than it would otherwise.
There's also a more traditional way to clean your catalytic converter which involves actually cleaning it by hand. To do this you have to remove the converter and use a pressure washer to clean off all the contaminants and build up. A thorough flush from both ends of the converter will get out a good portion of buildup and remove any potential clogs.
If the converter is clogged up bad enough you could also soak it overnight in some hot water and a degreasing agent. Even laundry soap can perform this task for you. You need to have some more patience to do this, but if you're not planning on driving anywhere overnight then it's not usually a big deal. Just make sure that you dry it thoroughly before putting it back in place. If this is all it takes to save you $2,000 on a new converter, it's probably worth your time.
The Bottom Line
Some drivers question why they need to have a catalytic converter on their vehicle at all if it's not important for the actual functioning of your vehicle. Since you can drive without one, why do you have it in the first place? The fact is that there are over 1 billion cars on the road today and they produce massive amounts of pollution. A properly functioning catalytic converter can reduce 90% of the dangerous emissions that come out of your exhaust. You're doing your small part to save the environment by having a catalytic converter that works properly. Not to mention that you're going to get a steep fine if you're caught without one. For those reasons, it's always a good idea to keep your catalytic converter working.