Catalytic converters are important to your vehicle and it helps to treat the exhaust system of toxic gases, so they don’t get released into the atmosphere. Catalytic converters contain catalytic substances, and this helps to convert the carbon monoxide found inside the toxic gas into carbon dioxide and water – this helps to clean the toxic gases efficiently to make sure that humans aren’t breathing in the toxic gases.
As you know, diesel engines are built for efficiency meaning that they use a completely different fuel from gas engines, and they ignite differently. This may leave you wondering if they have a catalytic converter that can help to get rid of the toxic gases in the exhaust system. Diesel engines use diesel fuel, and this is atomized and then ignited using a glow plug.
Do Diesels Have a Catalytic Converter?
Most diesel vehicles have a catalytic converter fitted because of legislation that protects the environment. Modern diesel vehicles have diesel particular filters or DPFs that work similar to catalytic converters – this filter helps to remove a greater number of pollutants in the exhaust gases but also removes soot. The diesel engines are cooler than the gas engine and produce fine carbon particles that haven’t been burnt to carbon monoxide. The particles are visible, so people think diesel engines gave more dirt and are more polluting than petrol.
Older diesel engines don’t have diesel catalytic converters, especially if they were made before 1990. Until 1990, there were technological advancements made to reduce emissions even without catalytic converters. Newer diesel engines built in Europe, especially all have catalytic converters installed.
Diesel converts have an Exhaust Gas Recirculation, Diesel Oxidization Catalyst, and Selective Catalytic Reduction as well as a Diesel Particulate Filter. Due to their use of catalytic to help facilitate chemical reactions to reduce emissions, the SOC and the DOC can be considered catalytic converters. The Diesel Oxidation Catalysts work identically to the cat converter in a gas engine. It uses metals as catalysts to help convert carbon monoxide into co2 and water.
These metals are also used to break down volatile chemicals such as hydrocarbons and nitrogen oxides. The SCR which can also be referred to as the Diesel Exhaust Fluid uses an ammonia-based catalyst to break down Nitrogen Oxide which is then converted to Nitrogen and Oxygen which isn’t harmful to humans.
Why Are Catalytic Converters Needed
Cars need catalytic converters because they produce toxic emissions that can damage the environment and once introduced into the air, it can cause acid rain which is toxic to humans. Other pollutants in this toxic gas can include Nitrogen oxides and Hydrocarbons. For decades, automakers have been trying to find new ways to reduce the number of toxic gases that have been produced by vehicles so in 1975, the cat converter was introduced. The Cat converter is now one of the most important parts of the emission control system.
It soon became law for all gas engines manufactured in the US and Europe to have catalytic converters fitted to meet standards. The diesel cars with their diesel particulate filters have also been made compulsory.
The Diesel Converter
The diesel engine and the gas engine don’t ignite in the same way. The gas engine uses a spark plug to ignite its fuel while a diesel engine will convert the fuel into a gas and then it’s ignited using a glow plug. This makes sure that the fuel is burned efficiently, and the amount of water fuel is low. Compared to a gas engine, the efficiency is poor because the ignition process isn’t efficient. To clean outgases, the diesel engine uses different systems than the gas engine. These systems are lined up in the diesel converter to make sure that the gases are cleaned properly.
Diesel Oxidation Catalyst – the diesel oxidation catalyst is the system that works more similarly to the system in the gas engine. The DOC is what is used to convert the carbon monoxide into carbon dioxide – it also breaks down any um-spent fuel. The DOC is the smallest component in the diesel engine, and it’s located in the front part of these converters. This part is made up of platinum and palladium which makes it the most recyclable part.
Diesel Particulate Filter – the diesel engine can produce soot, and this isn’t found in gas cat converters. The DFP can capture these particulates also known as soon by using a wall flow monolith. This is a filter that consists of open and closed channels and this allows the particulates to enter the convert from the inlet side and they’ll held in here until that can be broken down and moved out of these exhausts.
This process is called regeneration and it’s a similar process to what happens in the DOC system. An organic metal is burned to create CO2 and water which helps to break down the hydrocarbons. The DFP uses small amounts of platinum and palladium to help catalyze the reaction. The DPF needs to be at a high temperature to allow the soot to burn and pass through the filter and out the tailpipe. The control module which is the vehicle’s computer is what’s used to control the regeneration process.
Selective Catalytic Reduction – the SCR is in the middle part of the diesel converter and it’s just before the end which is the DPF – this section is also the largest but it has the least recycle value due to it’s material. It’s the part of the converter and reduces the Nitrogen oxides. In the SCR, Rhodium catalyzes the reduction reaction to reduce Nitrogen Oxides into gas and oxygen. Since there’s an abundance of oxygen in the diesel exhaust, rhodium can’t reduce the Nitrogen oxide gases in the diesel converter. Therefore, diesel converters don’t contain rhodium.
The SCR uses an additive called diesel exhaust fluid instead and this can be made up of ammonia or urea. The filter contains catalytic material, but they don’t have any recycling value. The DEF along with the catalytic materials can remove nitrogen oxides from the exhaust. In some diesel converters, the SCR has a small section called the ammonia slip catalyst and this contains a small amount of platinum. It’s meant to burn off excess amounts of ammonia from the DEF. This amount of platinum is so small that it can be recycled.
Another way the Nitrogen Oxides are reduced by is using a process called Exhaust Gas Re-circulation. For this process to occur, a SCR catalyst nor a DEF is needed. This means that not all diesel converters have an SCR that has an ammonia slip catalyst. The SCR and DPF are always towards the end of the DOC.
How Do Diesel Catalytic Converters Work?
The catalytic converter breaks down harmful compounds. It consists of a metal casing and there are two ceramic blocks that make up thousands of microcellular channels that look like a honeycomb. The ceramic blocks are coated with precious metals such as platinum, rhodium, and palladium. They’re located close to the engine so they heat up and this can cause a chemical reaction that breaks down the toxic gases, so they’re converted to carbon monoxide and vapor because they’re let out of the exhaust pipe.
The diesel oxidation catalytic is a diesel catalytic converter and it works similarly to catalytic converters in gas engines. It helps catalyze the reduction of carbon monoxide to water and carbon using metal catalysts. Volatile by-products and hydrocarbons are also broken down and turned into less harmful chemicals to prevent the exhaust from emitting harmful gasses.
The difference between petrol catalytic converters and diesel cat converters is that diesel-based cat converters have no rhodium and they come with a diesel particulate filter attached which helps to get rid of particulate matter found in petrol-based catalytic converters.
Also known as DEF, the SCR catalyzes the breakdown of oxides of nitrogen emission using ammonia-based catalysts which helps convert them to oxygen and nitrogen. As the redundant gases go over the SCR catalysts, the NOx emission converts to water and nitrogen in a chemical reaction.
When it comes to reducing NOx emissions in a diesel car, the open-loop SCR system is 75% to 90% effective. However, the closed-loop system found on stationary engines can reduce NOx emissions by about 95%. The SCR also reduces hydrocarbon emissions by about 80%.
A Trick So That Your Diesel Catalytic Converter Never Fails
If you have a diesel vehicle, you need to make sure that the cat converter is being looked after. If there’s a problem with the cat converter in your diesel vehicle, this can cause all sorts of problems with the engine. The cat converter is very easy to maintain, and this can increase it and the engine’s longevity. Failure to maintain these parts can lead to you visiting the dealership often to pay for minor problems.
If you want to avoid engine problems and save $100s of dollars that you’ll spend at the auto repair shop, you’ll need to service your vehicle often – you can use our mechanic-rated Auto Maintenance and Repair Manual to do this. It’s basically what mechanics use to go through your vehicle to check if there are any problems that need fixing. As soon as they notice the most minor problem, they’ll ask you to fork out some money even though it’s a problem you can fix yourself in minutes – the manual will teach you how to maintain your vehicle every few thousand miles and it’ll teach you how to fix minor problems that mechanics will ask you to pay for; saving you money in the long run.
A lot of our readers have the Auto Maintenance and Repair Manual printed on their garage wall and 92% of them haven’t visited the auto repair shop in the last year because they know what to do to avoid problems. All it takes is giving your vehicle a little attention every few thousand miles and you’ll never spend money at the workshop again.
Diesel Catalytic Converter vs Diesel Particulate Filter (DPF)
Diesel engine converters have been built to work specifically with diesel engines to filter particulates made in the engine. Engine emissions that come from diesel engines consist of particulates and unburned fuel emitted by the engine in the form of gas and vapor. The particulates are visible in the form of soot and can be seen as black smoke from the diesel engine’s exhaust. This is known to cause brown clouds of smog that can be found in industrialized cities.
Soluble organic fraction (SOF), lubricating oil hydrocarbon (LHC), and fuel-derived hydrocarbon (FHC) are the particulate solids that are found in most diesel engines. Over time, fuels like low sulfur diesel have lowered the number of particulate solids that emit from the exhaust into the atmosphere.
Because particulate is solid, it means that it can be filtered easily, and this is where the Diesel Particulate Filter that’s part of a diesel catalytic converter comes in. It removes the solid particulate from diesel emissions before it goes through the exhaust and into the atmosphere. The DPF consists of metal fibers, silicon carbide, or cordierite.
Improvements in Diesel Engine Performance and Emissions Reduction
Over the past decade, great improvements were made to the diesel engine. They are now smaller, cleaner, and more efficient. They are engineered to be efficient in their operation while being a lot more environmentally friendly.
Since 2010, the diesel engine has been made small, cleaner, and more efficient which means things are improving. They’ve been engineered to be environmentally friendly and efficient when operating. Before catalytic converters were introduced to diesel engines, there were still advancements made to make emissions cleaner. One advancement was the Diesel Oxidation Catalyst. This converted Carbon Monoxide to Carbon Dioxide and water.
The DOC came about in 200 and they were compulsory in all EU vehicles until 2011. After this, the next advancement was the DPF which helped to further lower emissions for diesel engines. It oxidizes some of the hydrocarbons that are absorbed in carbon particulates. It also traps soot from particulate solids which helps to lower the solid’s mass.
Does a Diesel Car Need a Converter?
If your diesel doesn’t have a converter, then the toxic gasses can’t be removed from the gases coming from the engine. If you have a vehicle that hasn’t got a catalytic converter or the cat converter isn’t working properly so toxic gases can’t be cleaned, you’ll have really high emissions. If there’s an unacceptable level of harmful emissions leaving the vehicle, your vehicle will fail it’s MOT, emissions test or smog tests which are all the same thing. It’s important that you maintain the catalytic converter and the engine to keep it in top shape.
How Long Does A Diesel Catalytic Converter Last?
You should be aware that diesel catalytic converters rarely become bad but even if they eventually do, how long would this take? Your diesel catalytic converter should last as long as your car but if it doesn’t it does tend to break around 100,000 miles. This depends on the length of the trips that the vehicle makes. A vehicle that makes short trips that tend to stop and start often should see the catalytic converter wear out quicker than a vehicle that makes long consistent trips.
When the engine has to switch back on, it takes the catalytic converter time to reach an optimum temperature range to catalyze reactions fully. Each time the catalytic converter has to reach an optimum temperature, the catalytic converter wears down slightly more. Although the catalytic converter has a long life span, it needs to be maintained just like any other component in your car.
How Much is a Diesel Catalytic Converter Worth?
There’s a demand for diesel catalytic converters and trying to determine the worth of your diesel catalytic converter is as crucial as trying to find out the worth of anything that hasn’t got a clear value. Diesel catalytic converters are relatively easy to sell since the global market for catalytic converters is large.
Diesel catalytic converters are often not worth too much money. This is because of the inexpensive materials used to make catalytic converters.
Because diesel catalytic converters are made up of inexpensive materials, they’re not worth too much money. Diesel catalytic converters are a common target for thieves due to the expensive materials used to make them. These precious metals include platinum, rhodium, or palladium. However, some diesel catalytic converters don’t use these precious metals and these catalytic converters aren’t as expensive.
Here are some average prices for different catalytic converters:
Large foreign catalytic converter: $202- $392
XL foreign catalytic converter: $398- $454
Foreign pre catalytic converter: $48- $71
Exotic catalytic converter: $225 – $450
High grade domestic catalytic converter: $145- $192
Pre- domestic catalytic converter: $27- $62
Torpedo catalytic converter: $80 – $250
Small catalytic converter: $83 – $158
Large catalytic converter: $154- $260
Large bread loaf catalytic converter: $138- $392
Small bread loaf catalytic converter: $104- $229
The foreign lite catalytic converter: $48- $75
Large Chrysler catalytic converter: $101- $189
The regular domestic catalytic converter: $68 – $104
Bread catalytic converter: $14 – $124
Diesel catalytic converter: $12- $124
Small foil catalytic converter: $12 – $ 32
Large foil catalytic converter: $29 – $64
Foil catalytic converter: $6 – $23
Half cat catalytic converter: Varies on different factors.
Aftermarket catalytic converter: $10
DPF catalytic converter: $9- $479
AC catalytic converter: $46 – $222
Are Diesel Catalytic Converters As Expensive As Gas Catalytic Converters?
Your average diesel catalytic converter isn’t as expensive as your average gasoline catalytic converter because the same precious methods that are used for petrol catalytic converters aren’t needed in a diesel-powered catalytic converter. These precious metals include rhodium, platinum, and palladium. Palladium has recently become more valuable than gold. Because of the value of these precious metals, gas catalytic converters are commonly stolen.
Although palladium is more valuable than gold, it doesn’t compare to rhodium which is valued at over $18,000 per ounce with Palladium sitting at around $3,000 per ounce and platinum is sitting at $1,000 per ounce.
Because diesel cats don’t need these precious metals to function, they can’t be sold for the same amount gas catalytic converters are sold at which is why they’re never targeted by thieves like petrol catalytic converters are. Considering that these metals are becoming so expensive, manufacturers are looking for different ways to accomplish the same goal of reducing harmful gasses while using materials that aren’t so precious and expensive.
Can You Drive Without a Diesel Catalytic Converter?
Many people ask questions like can I drive without a diesel catalytic converter? is it legal to drive an automobile without a catalytic converter? Is it safe to drive an automobile without the converter? How long can I drive without a converter? Can’t I just use a straight pipe? Here are the best answers to these types of questions:
Yes, you can drive without a diesel catalytic converter – The first automobiles were designed to run without a converter. It was not until emissions concerns came up in the mid 1970s that the idea of equipping every automobile with an emissions control device.
In countries with emissions standards (especially the EU), no you cannot drive without a converter – Most of the developed countries have rules to control the number of emissions in the air caused by motor vehicles. These countries have big cities with congested traffic, so the amount of fog and smoke is multiplied. The emissions regulations are enforced by required vehicle inspections. Car manufacturers must prove that new vehicles can pass an emissions test. The car owner also must prove that the vehicle can pass an emissions test during annual inspections.
People who drive older cars may have to have a catalytic converter added to their vehicle to pass the emissions test. When the idea of having an inspection to confirm the converter was working came about, some companies sold pipes to use for at home converter testing. Many people just used the much cheaper pipe and never replaced the converter. Others attach someone’s converter only for the inspection and then replace it with the pipe.
No, it is not safe to drive without a converter – When you drive an automobile without a converter, the smoke is coming out of the exhaust pipe, in the back of the car. You may not have to inhale that smoke, but the homeless man standing on the corner will when you stop at that traffic light. That bird perched in a tree is exposed to your unconverted smoke. From a broader perspective, it is not safe for the environment either. Your smoke is combined with the smoke of hundreds of thousands of other people on the road. That amount of exhaust is driving an increase in harmful greenhouse gases.
You can drive indefinitely without a converter – The automobile design does not require a catalytic converter. The purpose of the catalytic converter is to convert harmful emissions. You can drive without the converter. However, be aware that you are polluting the environment and in some places, breaking the law.
Cleaning A Diesel Catalytic Converter
Since the catalytic converter is used to clean out the gases in your diesel engine, you need to make sure that the converter is clean itself. To clean your catalytic converter, you can use a catalytic converter cleaner (View on Amazon). All you have to do is pour it into your fuel tank and it will help clean the entire catalytic converter. Along with this, it will also clean your O2 sensors and exhaust system. Your exhaust system is connected to the catalytic converters, so this gets cleaned as well at the catalytic converters. The cleaning works on any car, whether petrol, diesel, or hybrid.
To make sure you’re pouring the right amount into the fuel tank, you can read the service manual. If you want the cleaner to take full effect, you should drive for a few miles. Another way to get the catalytic converter clean and to burn off all the carbon deposits is to drive on the highway at a high RPM over a long period of time. This is going to get the catalytic converter really hot and this will burn off all the carbon deposits that are clogging it up. Cleaning the cat converter will make sure that your emissions are reduced, and the engine is protected.
How Much Do Diesel Catalytic Converters Cost to Repair/Replace
The average cost to repair a damaged diesel catalytic converter for most vehicles is between $900 and $2500 including parts and labor. For the catalytic converter to be replaced, it alone can cost on average $2250. If you were to get it fitted for just labor, this would cost between $200-$500 depending on the mechanic and the dealership you choose to go to. If charged by the hour, it can cost between $70 and $130. The whole job could take a few days or a few weeks depending on the dealership you go to. Repairing or replacing the catalytic converter can cost just as much as your car itself. In this case, you may as well get the car replaced if the cost to repair the cat converter is similar.
The high price for the repair is just the start. Before the repair, a diagnosis for the cat converter needs to take place to know what’s wrong with it in the first place. The bad cat converter can also affect other components in the vehicle, so these also need to be diagnosed. For example, the muffler, the tailpipe, or the O2 sensors might need replacing at the same time. Before the repair is done, make sure the dealership lays down the complete price so you can be sure whether you need to get your vehicle replaced.
The cost of the catalytic converter takes into consideration what the damage is on the cat converter. If the damages are minor, the cost of repairing the catalytic converter is going to be a lot less than if it was heavily damaged – the cost of getting new parts to repair the cat converter would cost more. The type of vehicle you’re getting the cat converter repaired on can also affect the price. A cat converter on a newer and larger vehicle is going to cost a lot more to repair and replace than one on an older vehicle. If the cat converter is too damaged, the dealership might recommend that the cat needs to be replaced completely – if this is the situation you find yourself in, you should look at replacing the car itself if the cost is similar.
Bad Diesel Catalytic Converter Symptoms
Just like any other part of your car, the catalytic converter can become worn out or damaged. The best way to tell if your catalytic converter is broken is to test it. First, here are some signs that your converter is not working:
Check Engine Light (CEL) – Sometimes the Check Engine Light (CEL) will activate on your dash to let you know something is wrong. You can use your OBD2 Scanner (view on Amazon) to see if the trouble codes are associated with your converter. You may get a P0420 “Catalyst System Efficiency Below Threshold (Bank 1)” trouble code, which means there is a problem with the catalytic converter or somewhere in the exhaust system.
You may also get a P0402 “Exhaust Gas Excessive Flow Detected” trouble code. This means that your engine control module has identified an issue with the engine exhaust gas recirculation (EGR) valve. The valve is often flooded with recirculated exhaust gases when this trouble code is recorded. The CEL will most like be activated and the vehicle is running roughly. In this state, the vehicle cannot pass any emission testing. There are other codes that are associated with the converter and other parts of the exhaust system, these are only examples.
Poor acceleration – When the catalytic converter is damaged, it causes your vehicle to accelerate slowly. It takes more time for you to take off. You may push the gas pedal to the floor and hardly move at all. This happens when the converter becomes clogged. Over time, other parts of the exhaust system may become damaged as well.
Hard Start/No Start – A symptom of a bad catalytic converter is when your engine will not start when you turn the key in the ignition. When the catalytic converter malfunctions, the engine may crank but it will not start. If the converter is really damaged, the engine may shut down.
Bad mileage – You will notice a significant drop in your mileage, as you will be going to the station much more often. You will only be able to go so far with less diesel. This is also because the converter is worn out for damaged. When the converter becomes clogged up, the exhaust becomes trapped in the engine.
Stalling – Gasoline engines stall for a number of reasons. The stalls can happen because of the catalytic converter being clogged or otherwise malfunctioning. The vehicle seems to start but doesn’t quite do it. This can cause real trouble. It means that something is not working properly. If it is affecting your engine, you know right away that it is important.
Rattling noises – when the converter is damaged, small parts may be rattling around inside. You can really hear the rattling when you first start your car. If it is not repaired, it will get worse over time. The converter Will have to be removed so that the components can be emptied out.