Your car's catalytic converter is part of the exhaust system, but it helps reduce the dangerous chemicals produced by your engine combustion reaction. Thanks to something called a redox reaction your catalytic converter is able to use a catalyst, which in this case is a precious metal like platinum or palladium, to convert harmful substances including carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful by-products as they go through your exhaust system.
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Typically, when your catalytic converter goes bad, you can expect to face a repair bill of around $900 to $2,500 to get your catalytic converter replaced. That's a pretty steep repair bill, and it's also a necessary one because you can't legally drive your vehicle without a catalytic converter. You can face some steep fines if you get caught without the converter, and you'll still need to replace the converter anyway, so there's no upside to driving without one.
If you're looking to save some money, and why wouldn't you, there is an alternative to simply shelling out the cash for a brand-new converter. You can potentially fix your catalytic converter on your own without having to actually go out and buy a new one. In many cases, a catalytic converter will stop functioning because it's clogged and dirty as opposed to broken. That means there are things you can do to get it working again that won't cost you nearly as much as replacing the entire unit.
Signs and Symptoms of a Bad Catalytic Converter
As part of your exhaust system it's often difficult to notice that there's anything wrong with your catalytic converter because it's not the kind of thing you're going to be looking at all the time. That said, there are a number of signs and symptoms you can be on the lookout for her to let you know you're having a problem with your catalytic converter that may require some repairs.
Unusual Noises
Every driver should be aware of the typical sounds that their car makes when they're out on the road. That's because when noises change it's a great indication that something is wrong, so you should be familiar with the regular sounds so that you can pick out the irregular ones more easily.
When you have a problem with your catalytic converter you will likely start noticing a rattling sound. This is caused because the catalyst metal itself, the platinum, rhodium or palladium we mentioned earlier, is manufactured in a honeycomb pattern of ceramic or similar material inside the converter. Those little honeycomb parts can break off and crumble over time and they will rattle around inside like a stone in a tin can. As more break off, the more noticeable the rattle will get.
Poor Engine Performance
If your catalytic converter is too badly clogged that's going to decrease your engine's ability to perform the way you expect it to. That's because your engine won't be able to vent exhaust the way it normally does because the converter is clogged for venting the natural flow of gases.
Poor Gas Mileage
Much like the poor engine performance, the clog in your converter will also cause your gas mileage to suffer as a result. The exhaust is going to be pushing back into your engine which will alter your fuel and air ratio and affect the combustion reaction. This is going to cause a noticeable decrease in your gas mileage and in turn means you're going to be spending more money on gas but getting less performance out of it.
Sulphur Smell
Because a failing catalytic converter can no longer properly convert the toxic fumes that flow through it into less harmful materials, one of the side effects that you are going to experience is the smell produced by the gases flowing through it. In particular the exhaust is going to have a sulphur type smell.
When your car burns gasoline one of the normal by-products that it creates is hydrogen sulfide. The catalytic converter is necessary to convert hydrogen sulfide into sulphur dioxide which is less harmful. However, if it's not working then this process can’t take place and the end result is a smell that's not unlike rotten eggs. You'll likely also notice that your exhaust is much darker than it should be, potentially a grey to black smoke.
Check Engine Light
Just like with many other problems in your vehicle if the catalytic converter isn't working properly it's possible that it's going to set off the check engine light on your dashboard. Since the check engine light can go off for any number of reasons you'll likely have to rely on some of these other symptoms as well to know for sure if your catalytic converter is the source of the problem or if it's something else.
The best thing that you can do when you see your check engine light on your dashboard is to invest in an OBD2 scanner. These scanners, also known as on-board diagnostic tools, are what mechanics used to diagnose the warning lights that will come up on your dashboard. You just have to plug it into your vehicle, and it will give you a code that corresponds to the specific problem that caused the light to come on in the first place. You can buy a cheap one on Amazon for around $30 that can at least direct you towards the problem so you don't have to guess what might be wrong. It is related to your catalytic converter, at least then you'll know without having to do a lot of trial and error.
How to Clean Your Car's Catalytic Converter
So, as you can see, there are a number of different ways that your catalytic converter is going to let you know that there's a problem with it. And of course, you don't want to be going out of your way to spend between $900 and $2,500 to get it repaired if you don't actually need to do that. When it comes to cleaning out your catalytic converter you can definitely handle this job on your own without taking it to a mechanic if you know what to do.
The Italian Tune-Up
You may have not heard of this before and it's definitely not a manufacturer-sanctioned way to fix a problem with your vehicle, but some drivers will pull out what they call the Italian tune-up to fix problems with their vehicle that can include an issue with the catalytic converter.
As it happens, many drivers stick to driving in the city at low speeds and don't actually get their car pushed hard enough to get the catalytic converter at its most efficient operating temperature. Ideally your catalytic converter is operating between 800 degrees Fahrenheit and 1,832 degrees Fahrenheit. That's 426 degrees Celsius and 1000 degrees Celsius. Very hot to be sure, but that's what your catalytic converter is supposed to be doing. If you take it easy on your car all the time, your converter is not going to hit those temperatures and that actually can lead to premature failure because it's not able to function the way it's supposed to.
An Italian tune up is when you push your car to the limits for at least a few miles. That means you get it on a stretch of open road and hit the accelerator hard. Get it up to a pretty impressive speed, lay off on the accelerator for a minute, then hit it again. You do this a few times in a row, ensuring that your engine is performing as hard as it can, and it's actually possible to heat up your converter enough to burn off some of the deposits in the intake, the cylinder heads, the oxygen sensors, throughout your exhaust and into the catalytic converter.
This isn't a guaranteed fix by any means, and if your converter is too badly clogged that probably won't work, but if you just started experiencing problems this may actually get the job done. Just remember, if you're going to try this, be safe about it and by no means should you be breaking any speed limits or putting yourself or other drivers in danger.
Fuel Additives
There are many fuel additives you can buy that are meant to help your engine run more cleanly and that includes the catalytic converter. Any time you go to the gas station you likely have three choices for the kinds of gasoline you put in there: standard, premium and some kind of super premium gasoline. The reason those fuels cost more is they have fuel line additives added to them that will help your engine run a little bit better. That's not just a scam to make money off you, those things actually do work. If your catalytic converter is starting to give you trouble, then you may want to run a few tanks of high-quality gas through it. The next two or three fill ups, use better quality gasoline or just buy a bottle of cleaner that can help to clean out your catalytic converter as you're driving and pour that into the tank as well.
Another option that some mechanics will recommend is something called lacquer thinner. You can buy a gallon of lacquer thinner and pour that into your gas tank when it's about half full. From there you can hit the road at a high rate of speed and drive for a good 150 miles or so. If that's not an option, and let's be honest most of us aren’t going to take a 150 mile road trip anytime soon for no reason, you can also just run the engine at 2500 rpm when you're in your driveway for about half an hour.
This will get your converter up to a good temperature and can burn out all those impurities that have built up inside of it allowing it to work properly again. Compare that to a $2,500 repair bill, and the choice of what to do is pretty clear.
Old Fashioned Cleaning
Sometimes the best way to clean your catalytic converter is to simply remove it and use a pressure washer to wash off all the contaminants that have built up on the inside. You just need to flush it from both ends to ensure your maximum coverage here and you should notice some improved results.
Alternately, for a little deeper cleaning, you could soak your catalytic converter overnight in hot water and a typical degreaser or laundry detergent. Something that's designed to break down tough grease buildup. Obviously this is going to take longer, but if you're done driving for the night and you have some time to spare, it couldn't hurt to give it a soak, then give it a power wash, and make sure you dry it thoroughly before you put it back in place.
The Bottom Line
The entire point of your catalytic converter is to pull contaminants out of your exhaust so that your car runs more smoothly and is less polluting. It's going to get dirty and clogged up at some point in time but the way you take care of it can really help prevent it from getting too bad. One of the best things you can do to prevent clogs in your catalytic converter is to head out for a 20- or 30-minute drive once a week during which you reach highway speeds. Just schedule some time for a short road trip outside of the city maybe on a weekend and then head back home again. This will allow your converter to get up to that optimal operating temperature and it will actually burn off a lot of this excess build up, so you don't have to deal with clogs.
If it does happen that your catalytic converter is giving you signs that there's a problem, just remember that there are options you can take care of on your own before you have to rely on heading to a mechanic and shelling out for a very expensive repair bill. Sometimes all you need is a little elbow grease and some ingenuity to get a problem fixed and the price tag will be much lower than what a mechanic is going to set you back.