- 1 Why is there an exhaust emission test?
- 2 What emissions are measured in an MOT?
- 3 Is exhaust noise part of MOT?
- 4 How do you measure exhaust emissions?
- 5 What counts as emissions?
- 5.1 Is an MOT wash necessary?
- 5.2 How can MOT reduce exhaust emissions?
- 5.3 What is the most common failure on an MOT?
- 5.4 What happens if you don’t get your exhaust fixed?
- 5.5 What happens if you keep driving with a bad exhaust?
- 6 What happens if you ignore an exhaust leak?
- 7 What is considered an exhaust leak?
- 8 Is the exhaust part of the emissions system?
Do MOT tests include an exhaust emission test?
MOT – Most vehicles have their exhaust emissions tested as part of the MOT. Usually, they’re tested using a meter. Petrol vehicles used before August 1975 and diesel vehicles used before January 1980 are tested by sight. If your vehicle fails the emission test it fails the MOT.
vehicles with fewer than 4 wheels vehicles with 2-stroke engines hybrid vehicles quadricycles hydrogen fuel cell vehicles electric vehicles
Why is there an exhaust emission test?
Why do MOT tests include an exhaust emission test? – An exhaust emission test looks at the level of pollutants that are emitted from the exhaust of your car, with the aim to reduce the amount of harmful pollutants to the environment. Diesel and petrol emission tests are different but are both tested as part of an MOT,
Petrol – the emission test measures gasses that exit the exhaust. Diesel – the emission test measures opacity using light.
Emission tests are carried out to make sure that your vehicle’s engine is functioning efficiently so that any pollution created by the engine is kept to a minimum.
What emissions are measured in an MOT?
Know More – MOT Test of Exhaust and Emissions In 2018, the DVSA added emission tests to the MOT. MOT Centres now assess the amount of carbon monoxide and hydrocarbons in your vehicle emissions as part of an MOT. They’ll also check for nitrogen oxide levels if you drive a diesel vehicle.
- Every year, automobiles get cleaner and more efficient.
- If your car is in good running order, your emissions should always be within a few per cent of what the manufacturer recommends.
- So, if you’re driving a new vehicle, you’re unlikely to fail your MOT because of emissions.
- However, driving an older vehicle particularly a diesel car, you risk failing an MOT due to high emissions.
If your vehicle’s exhaust emissions are too high, you won’t be able to receive an MOT certificate. Emissions can also be checked as part of a routine roadside inspection. The exhaust emissions of most automobiles are evaluated as part of the MOT. A gauge is usually used to test them.
- Vehicles manufactured before August 1975 and diesel vehicles manufactured before January 1980 are visual inspections.
- Your vehicle will fail the MOT if it fails the emission test.
- Before you may acquire an MOT certificate, you must solve the problem.
- We have included all types of MOT Exhaust and Emissions testing equipment to help our students’ learning at our MOT Test Course training centre in Northampton.
Also, in our MOT Annual Training curriculum, we had made it available about the latest trends in Exhausts and Emissions testing standards. The exhaust system and the emissions produced by the exhaust system are both tested during the MOT. Under the new category of ‘Nuisance,’ the May 2018 version of the MOT Testing Manual unites exhaust emissions with noise and fluid emissions.
- Noise Suppression System
- The MOT Tester will look at the following items • Exhaust silencers • Under-bonnet noise deadening material.
Exhaust noise will be measured during the vehicle’s emissions test or by reviewing the engine to roughly 2,500rpm or half the maximum engine speed if the top engine speed is lower on vehicles that are not subject to an emissions test. The vehicle’s exhaust noise shall not be excessively higher than the noise level ordinarily expected from a similar vehicle with a standard silencer in good condition.
Spark Ignition Engine Emissions It is a kind of MOT inspection exclusively for vehicles requiring a complete catalyst emissions test. Only visible and identifiable components will be examined, such as catalytic converters, oxygen sensors, and exhaust gas recirculation valves. The exhaust system will fail the MOT if the following conditions exist • A component of the system is missing or has significantly deteriorated.
• The exhaust system is insecure because mountings are missing or broken. • There is a significant leak.
- • The system produces far more noise than a comparable vehicle with a working standard system.
- Diesel Compression Ignition Engine Emissions
Only apparent and recognisable components will be tested, such as diesel oxidation catalysts, diesel particle filters, exhaust gas recirculation valves, and selective catalytic reduction valves. If a diesel particulate filter has been sliced open and rewelded, it will be refused unless you can demonstrate a genuine purpose for the cut, such as filter cleaning.
MOT Training for the future MOT Testers has in-depth learning in Exhaust and Emissions system. Diesel Emissions Opacity The MOT Tester will ensure that your vehicle is appropriately prepared for a diesel emissions test and safe to do so. If the vehicle were first utilised on or after January 1, 1980, a diesel smoke metre would be used.
If the Tester determines that conducting the smoke test on the VT30 is dangerous, you will be informed of the reason for the refusal. The MOT Documentation training is also offered to our students who have registered for our MOT Test Course. If any of the following conditions exist, the smoke test will be cancelled • There isn’t enough oil in the engine.
Is exhaust noise part of MOT?
Horn And Lights – Your nearest MOT test centre will test your horn to ensure it’s in full working condition and that it is a suitable type. It has to work properly as your horn is a vital component in case of an emergency. For example, if you see an accident about to happen or you might be involved in one, your horn can draw attention to and help prevent or reduce the impact of a road accident.
- We don’t have to tell your that your headlights must be fully operational.
- Not only do they allow you to see at night or in adverse weather conditions but they also make it easier for others to see you.
- An MOT centre will check their condition and that they all work properly, including HID and LED headlamps for cleaning, self-levelling and security.
They also look at the aim of the headlight and main beam warning light. If your headlights are faulty, you could be putting yourself and others at risk without even realising.
Is exhaust an MOT failure?
Spark ignition engine emissions The exhaust system will fail the MOT if: Part of the system missing or excessively deteriorated. Mounting are missing or damaged so that the exhaust system is insecure. There is a major leak.
Will a car pass an MOT with an exhaust leak?
Failed MOT – A vehicle which has a severely damaged or broken exhaust will automatically fail due to emissions, but it can also fail if it produces too much noise – usually related to issues with the silencer. Either way, if you’ve left your exhaust to deteriorate over the years – whether due to damage or wear and tear – you’ll likely be facing higher repair fees.
How do you clear exhaust emissions?
Install a diesel particulate filter (DPF) – If you have a diesel car which was manufactured after 2011, then you do not need to worry about this one, as you will already have a diesel particulate filter fitted. If you have a car which was manufactured before 2011, it is advised that you have a DPF installed.
How do you measure exhaust emissions?
3 ENGINE TEST EQUIPMENT AND PROCEDURE – The performances and exhaust emissions of eucalyptus biodiesel and its blends with diesel are evaluated and compared with diesel fuel ones. For this purpose, constant speed engine tests are carried out on a single cylinder DI air cooled LISTER PETTER (TS1) diesel engine developing a power output of 4.5 kW at 1500 rpm.
- The experimental set up schematic is shown in Fig.1 and the engine details are given in Table 3,
- An electrical dynamometer is used for loading the engine.
- An orifice meter connected to a large tank is attached to the engine intake manifold to make air flow measurements.
- The fuel flow rate is measured with a Coriolis mass flow meter.
This meter uses the Coriolis effect to measure the amount of fuel moving through the element. Chromel-alumel thermocouple in conjunction with a slow speed digital data acquisition system is used for measuring the exhaust gas temperature. An exhaust analyzer (COSMA) is used for measuring hydrocarbons (HC) by a flame ionization detector while carbon monoxide (CO) emissions are measured using an infrared device. Figure 1, Photographic view of the experimental setup 1– Diesel engine 2– Gas analyzer 3– Particulate analyzer 4– Diesel tank 5– Biodiesel tank 6– Orifice meter 7– Air tank 8– Wires of different sensors. Table 3, Specifications of the engine used
|Type||Naturally aspirated, four stroke, single cylinder,|
|DI, compression ignition|
|Bore and stroke||95.3 mm X 88.9 mm|
|Displacement volume||630 cc|
|Connecting rod length||165.3|
|Fuel injection timing||20° before TDC|
|Rated power output||4.5 kW at 1500 rpm|
A high-speed digital data acquisition system in connection with two AVL piezoelectric transducers is used for measuring the cylinder pressure and fuel line pressure histories. An optical shaft position encoder is used to give signals at TDC. Engine in-cylinder pressure and crank angle signals are sampled for 100 consecutive cycles at the increments of 0.1 crank angle intervals.
- Before each experiment, the engine is regulated according to the manufacturer catalogue values.
- All data are collected after the engine stabilization.
- During the entire investigations, the working parameters of the test engine are fixed as: injection timing of 20°CA before TDC, engine speed of 1500 rpm, and compression ratio of 18.
Experiments are performed with neat eucalyptus biodiesel and its blends with diesel fuel (75% eucalyptus biodiesel, 50% and 25% proportions by volume) at various engine power outputs (0.9, 2.25, 3.15 and 4.05 kW). The legend EBX represents a blend including X% biodiesel (i.e.
- EB100 represents neat eucalyptus biodiesel).
- Readings of engine speed, fuel flow rate, air flow rate, exhaust gas temperature etc.
- Are recorded and analyzed in order to determine engine performance parameters.
- Exhaust gas analyzers are calibrated carefully before making measurements, based on the manufacturer’s recommended procedure.
Observations are made for smoke, NO, HC and CO to analyze the emissions characteristics. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780857092052500147
What causes MOT emissions failure?
The ‘quality’ of a vehicle’s exhaust gases is graded in ‘Lambda’, which is a calculated measurement. If there are a huge number of hydrocarbons or the Lambda value is not within the correct range, a car is likely to fail its MOT.
What counts as emissions?
What are Greenhouse Gas (GHG) emissions? – Greenhouse Gas (GHG) emissions are broken down into three categories: scope 1, scope 2, and scope 3. The Greenhouse Gas Protocol created these scopes as part of its Corporate Accounting Reporting Standard to provide a global framework for measuring and managing GHG emissions for all types of organisations and industries.
This framework helps to prevent the “double-counting” of emissions in company reporting. Emissions are gases and other particles that are released into the atmosphere because of human activities such as burning fuels. Generally, these emissions are most likely to come from cars, power generation, and industrial processes.
When greenhouse gases are released into the atmosphere, they are capable of absorbing infrared radiation. Consequently, this process will trap and hold heat in the Earth’s atmosphere, causing what is known as global warming. The most impactful greenhouse gases emitted by humans include carbon dioxide (CO2), methane (CH4), nitrous Oxide (NO2), and Fluorinated Gases,
A greenhouse gas emission is when one or more of these greenhouse gases are released into the atmosphere. A carbon footprint (also called carbon emissions) is measured in tonnes of greenhouse gas emissions which are converted into carbon dioxide equivalent (CO2e), a standard unit for measuring carbon footprints.
CO2e presents the carbon footprint as a single number with the same global warming potential as the sum of the three main greenhouse gases measured. Figure 1: GHG Protocol, Scopes 1, 2, and 3 emissions. Adapted by Compare Your Footprint.
Is an MOT wash necessary?
Preparing for a vehicle test – Your vehicle should be road worthy and in full working order, so it is advisable to have it checked by a mechanic before the test. You must also make sure that the exterior, interior and underparts of the vehicle are clean or the examiner may refuse to test it.
If your vehicle is not a standard production type car or has been modified to sit lower to the ground – or has any part which may sit too low to the ground such as a front spoiler, exhaust or mud flaps you should contact your local test centre for guidance before bringing the vehicle for its annual test.
You can see the Vehicle Inspection Manuals online at:
- Light vehicle inspection manual
- Heavy vehicle inspection manual
- Motor bicycle inspection manual
What is checked on exhaust system?
Exhaust System – Question: Exhaust Inspection – What is it? Answer: An exhaust inspection is a very simple, but very critical service. The inspection includes a visual examination of the exhaust manifold to the tail pipe. All parts in between, including the catalytic converter, muffler, and pipes, are inspected.
An exhaust inspection is required to control your vehicle’s emissions and to make sure your vehicle will pass an emissions test. In a typical four-stroke combustion engine your engine goes through four phases: intake, compression, combustion, and exhaust. During the intake stroke the intake valve opens, while the piston moves down, and allows air and gas to mix in the engine.
Next, in the compression stroke the piston moves back up to compress the air/fuel mixture. In the combustion stroke your engine’s spark plug ignites the air/fuel mixture, while the piston moves down. Finally, during the exhaust stroke the piston moves back up as the exhaust valve opens to let the air/fuel mixture enter the exhaust manifold and travel through the exhaust system.
- The exhaust manifold, the first part of your vehicle’s exhaust system, is attached right to your engine.
- The fuel/air mixture from all of your engine’s cylinders, whether you have a four, six, or eight cylinder engine, will end up in an exhaust manifold.
- The manifold receives the burnt engine gases and will completely burn any unused or incomplete burnt gas.
The manifold also houses the first oxygen sensor in your exhaust system to inspect the amount of oxygen entering the system. The oxygen sensor monitors the amount of oxygen and will tell the fuel injection system to increase or decrease the amount of oxygen used in the fuel/air mixture used to power the engine.
The sensor also makes sure there is enough oxygen in the exhaust system to be used by the catalytic converter. The manifold then sends emissions through the exhaust pipes and into the catalytic converter.Your engine produces many harmful gases, which the catalytic converter must control. Catalytic converters contain substances or compounds such as platinum, rhodium, and palladium that react with, and convert, these harmful emissions.
Catalytic converters react with, and convert, harmful gases such as carbon monoxide, hydrocarbons, and nitrogen oxides produced by your engine into less harmful gases before they travel out your exhaust system and into the air. Once these harmful substances travel through the catalytic converter, the exhaust pipes send the emissions into the muffler.Your vehicle’s muffler aids in dampening emissions as well as engine noise.
Mufflers are mainly used to dissipate the loud sounds created by the engine’s pistons and valves. Every time your exhaust valve opens, a large burst of the burnt gases used during your engine’s combustion is released into the exhaust system. This release of gases creates very powerful sound waves. Finally, once your engine’s emissions travel through the muffler, they are released into the atmosphere through your vehicle’s tailpipe.
During an exhaust inspection, all of the exhaust system’s parts are visually inspected for any cracks or other damage. All of the clamps, mounts, and gaskets are also inspected. Then each exhaust system part (exhaust manifold, catalytic converter, muffler, pipes, and tailpipe) is checked to make sure it is working properly and controlling your engine’s emissions.
How can MOT reduce exhaust emissions?
The use of catalytic converter and fuel injector cleaners before an MOT is another effective method of reducing car emissions. They work by being poured straight into your fuel tank and mixing with the fuel. This mixture then goes through the combustion cycle to clean out the fuel injectors, engine and exhaust system.
What is not included in an MOT?
It doesn’t cover the condition of the engine, clutch and gearbox. To find your nearest authorised MOT test centre, visit these websites:
- England, Wales and Scotland – UK MOT
- Northern Ireland – NIDirect and book a test online
An average MOT test takes between 45 and 60 minutes, but there are a couple of other things to take into consideration. First, if your vehicle fails the test and repairs are needed this will take longer. A test centre isn’t allowed to let you drive away a car that has failed an MOT until the problems are fixed, unless your existing MOT certificate is still valid, or you’re taking the car to have the faults fixed.
- Second, the test might take an hour or less, but, even if there aren’t any repairs, this doesn’t mean your vehicle will only have to be at the garage for 60 minutes.
- Test centres can require you to drop your vehicle off first thing in the morning and collect it when ready.
- This means you should be prepared to be without your vehicle for the day.
The Vehicle and Operator Services Agency sets the maximum fee official test centres can charge for an MOT. It’s currently £54.85 for cars and motor caravans and £29.65 for motorbikes, but many garages charge less than this – sometimes up to 50% less. Search online for “cheap MOT” or “MOT discount” to find out how you can save money on your car’s next MOT.
An MOT might also be included in the cost of a full service for your car. While servicing your car regularly is a good idea, a service, even if it includes an MOT, is likely to be more expensive than an MOT on it’s own. Nearly two in five MOT tests fail first time. Yet often this is because of minor faults the owner could easily have fixed themselves before they paid for a test.
Here are some of the ways your car could fail an MOT.
- Screen wash not topped up. This basic task takes minutes, so don’t be caught out by it.
- The car was dirty or full of clutter. Clear the mess from the boot and cabin and give the windows and mirrors a quick wipe.
- A registration plate problem. For example, the plate used the incorrect type face/spacing, or was dirty or missing altogether. If you have a personalised plate, make sure it follows DVLA rules.
- Stickers on the windscreen blocking the driver’s view. Make sure anything stuck to the windscreen like parking permits is outside the wipers’ sweep area.
- Lit-up warning light on the dashboard. The MOT has included lit-up warning lights since 2012. So make sure you know what lit-up car warning lights mean and, if you have, any sort out the underlying problem before the MOT.
This can easily be done with a 20p coin – see the diagram at Tyre Safe Check for any damage such as splits in the tread, bulges or cuts in the sidewalls. Also check the tyre pressure is correct – the car’s manual will list the right pressure and they might also be on the sidewall of the tyre itself – and increase it at a petrol station if necessary.
- The handbrake: check the tension in your handbrake.
- If it slides up and down without resistance and can’t be ratcheted to a set level, there’s likely to be a problem needing fixing by a professional mechanic.
- Seats and seatbelts: check the driver’s seat adjusts forwards and backwards and inspect the full length of the seatbelt for any damage.
Check all the seatbelts latch and fasten securely, and lock when you give them a sharp tug. Windscreen: any damage wider than 10mm in the driver’s central view will cause an MOT fail, as will any damage larger than 40mm in the whole of the swept area.
Windscreen wipers: make sure your wipers clean your windscreen effectively along with the washers. Remember, any tears or holes in the wiper rubber can mean an MOT fail. Suspension check: check the shock absorbers by applying your weight to each corner of the car then quickly releasing it. The corner of the car should quickly return to its original position.
If it bounces more than twice, this could mean the shock absorbers are faulty and need to be checked. Horn: give a short blast of the horn – if it doesn’t work or isn’t loud enough to attract the attention of pedestrians or other motorists, get it repaired.
Exhaust: check for exhaust leaks by starting the engine in a well-ventilated space at normal temperature, then listen from the rear of the car for any unusual noises or abnormal smoke. Fuel and engine oil: make sure your car is filled with enough fuel and engine oil – you can be turned away from the MOT if there isn’t enough to test your car’s emissions levels properly.
If your car fails its MOT, the test centre will give you a VT3O Certificate showing the reasons for the fail. On 20 May 2018, the MOT categories for fails and passes changed. If your car has a dangerous fault, you won’t be able to drive it away. Get a quote from the garage you got the MOT from if they do repairs, and then call around for some quotes from other local garages.
You might be able to find the repairs cheaper even if they need to tow your vehicle to their garage. If your car has a major fault you may be able to drive it away if it’s still roadworthy Opens in a new window and your previous MOT has not expired yet. If your MOT has run out and the car is roadworthy you can drive it to have the faults fixed and to a pre-booked MOT.
If you drive a car without an MOT under any other circumstances, or drive a car with dangerous faults, you can be fined £2,500, be banned from driving and get three points on your licence. You need to fix all major and dangerous faults to make your car roadworthy and then arrange a partial MOT retest in which your car must pass before you can drive it on the roads again.
If you leave your car with the test centre for repair, you’ll be able to get a partial retest for free, as long as this is done within 10 working days of failing the MOT. If you take your vehicle away for repairs, and return it before the end of the next working day, the test is normally free. Whether it’s free or not depends on which parts are retested If you return within 10 working days to the same test centre for a partial retest, you’ll get charged a lower fee, but it won’t be free.
If your MOT has expired, it’s illegal to drive your car on the road and you could be prosecuted for doing so. Driving without a current MOT also invalidates your car insurance. So you might not be covered if you were to have an accident. The only exception would be if you already had an MOT booked and were driving your car to the test.
- There are two ways to get a replacement MOT test certificate.
- The first is free.
- Just go to GOV.UK where you can view, print and save any MOT certificate issued after 20 May 2018.
- All you need is the vehicle’s registration number and the 11-digit reference number, with no spaces, from the vehicle’s V5C, also known as a logbook.
The second way costs £10. You can go to any MOT test centre and give them your vehicle’s registration number and the V5C reference number. You don’t need a MOT certificate to sell a vehicle, but many buyers will want to see it. You also need an MOT certificate to tax your vehicle and to change the vehicle’s tax class, such as getting free tax for a disabled driver.
What is the most common failure on an MOT?
1. Lighting and signalling (18.9%) – Nearly a fifth of all cars which fail their MOT are because of an issue with their lights. Often, this will be as simple as a blown bulb. Switch all your lights on and walk around your car to check they’re in working order.
What happens if you don’t get your exhaust fixed?
Your car’s exhaust system routes exhaust gases away from the passenger cabin. If there’s a problem with the system, however, exhaust fumes can enter the cabin, and you could end up breathing in harmful gases. A small exhaust leak can cause your car’s engine to run less efficiently, costing you more money in gas.
What happens if you keep driving with a bad exhaust?
Damage to Other Car Parts – Over time, the fumes leaking from a cracked exhaust pipe will damage surrounding components, and could even cause a fire. When they first come out of the engine, exhaust fumes are extremely hot, but cool gradually as they reach the tailpipe at the back of the vehicle.
- If there’s a hole in the exhaust close to the engine, these hot gases can leak out and blow straight at other components — causing heat damage and increasing the risk of fire.
- The impact leaking exhaust fumes will have on other bits and bobs beneath the car will differ depending on where the hole is located on the exhaust system.
The closer the hole is to the tailpipe, the smaller the impact will be on surrounding parts.
What happens if you ignore an exhaust leak?
Signs of an Exhaust Leak Responsible for reducing the emissions your vehicle produces, your exhaust system makes these toxic gases less harmful before they leave your car and are released into the environment. A properly working exhaust system is essential for the safe operation of your vehicle.
An exhaust leak can cause dangerous gases to enter the atmosphere before being properly treated, which can cause problems like fumes in the cabin and failed emissions inspections. Many of these harmful gases are odorless, which means that you won’t realize they are leaking into the passenger cabin. Prolonged exposure to these emissions could make you and your passengers sick.
If you live in a state with emissions testing, an exhaust leak can result in failing the test, forcing you to resolve the issue before being able to legally operate your vehicle. Keep your vehicle running smoothly – learn to recognize the symptoms of an exhaust leak. Engine Noise Increased engine noise is a common sign of an exhaust leak. Listen for a loud rumble, especially while accelerating. You may also hear intermittent popping or hissing noises while the engine is running. Loss of Acceleration and Power An exhaust leak can affect the performance of your engine. You may notice that your vehicle doesn’t have its usual pick-up-and-go when you punch down the gas pedal. Your vehicle will continue to lose power if the exhaust leak isn’t fixed. Reduced Fuel Economy If you’re making more trips to the gas station, an exhaust leak could be the culprit. When your vehicle has an exhaust leak, your air-to-fuel ratio balance could be disrupted. Improper air-to-fuel ratio can cause the engine to run less efficiently, causing it to reduce overall engine efficiency. Gas Smell Smelling gas fumes inside your vehicle can be a sign of an exhaust leak. If an exhaust pipe becomes damaged it can let gas fumes escape into the passenger cabin of your vehicle.
What is considered an exhaust leak?
If there’s a burning aroma lingering in your cabin (and you didn’t just drive by a smokestack) Exhaust Leak service should go right to the top of your To-Do list. Behind those yucky fumes you smell, more poisonous gasses may be sneaking into your cabin – that you can’t smell.
Since you can’t always smell an exhaust leak, pay attention to any changes in your vehicle’s acceleration performance. Book an appointment at the first sign of sluggish pickup, backfiring, funny noises, or a vibrating gas pedal. (Better yet: have your exhaust system checked regularly at Midas.) An exhaust leak is a hole (or other defect) in your vehicle’s exhaust system that lets toxic exhaust fumes enter your cabin instead of exiting your vehicle through the tailpipe.
Engine exhaust contains poisonous gasses like carbon monoxide, nitrogen oxides, phosphorus, metals such as lead, and unburned fuel (hydrocarbons). An exhaust leak can endanger you and your passengers if the fumes build up in your cabin faster than your car’s ventilation system can evacuate them.
Exhaust valve and piston: Engine parts that force exhaust fumes out from the combustion chamber (where they are created) to the exhaust manifold. Exhaust manifold: The path from the piston to the catalytic converter. Catalytic converter: Converts some toxins to carbon dioxide (CO2) and water for cleaner emissions – though the exhaust is still poisonous in confined spaces (and CO2 is a greenhouse gas). Exhaust pipe: Carries the cleaner exhaust gasses to the muffler. Muffler: Reduces the noise of combustion and expulsion of exhaust. Tailpipe: Where exhaust leaves your vehicle.
Does a car need a catalytic converter to pass MOT?
This week in our “Getting to Know” series, we take a look at what catalytic converters are and what their job is. What is a catalytic converter? The role of a catalytic converter is to reduce the level of toxic gases which are released from the exhaust. All petrol cars in the UK from 1992 onwards have had to have a catalytic converter fitted as standard in order to comply with emissions regulations.
- Today, it is a legal requirement for a car to have a catalytic converter in order to pass the MOT test.
- Where is it located on a vehicle? A catalytic converter, which is cylindrical in shape, can be found within a vehicle’s exhaust system, often close to the manifold (the component that joins the exhaust to the engine).
Catalytic converters are far more efficient when hot, and their optimal working temperature ranges between 350 to 400 degrees Celsius. How does a catalytic converter work? Noxious gases are converted into carbon dioxide, nitrogen and water by passing over a fine honeycomb structure that is plated with precious metals such as platinum, palladium and rhodium.
It’s these metals which start the chemical reactions. What is the lifespan of a catalytic converter? A catalytic converter will often last as long as the vehicle, based on the catalytic converter being an original equipment manufacturer (OEM) device, which is made from high quality materials. It tends to be an expensive component to replace, and prices can vary depending on the make and model of the car.
What can cause damage to a catalytic converter? Various factors can reduce the effectiveness of a catalytic converter. These can include an out-of-tune engine which could be the result of misfiring spark plugs or an incorrect fuel mixture and engine timing, excessive fuel, oil entering the exhaust and damage from debris on the road.
What does MOT test include?
An MOT involves dozens of checks on your car, ranging from the brakes and fuel system to lights, mirrors, seatbelts, windscreen wipers and exhaust system. It doesn’t cover the condition of the engine, clutch and gearbox.
Is the exhaust part of the emissions system?
emission control system, in automobiles, means employed to limit the discharge of noxious gases from the internal-combustion engine and other components. There are three main sources of these gases: the engine exhaust, the crankcase, and the fuel tank and carburetor.
The exhaust pipe discharges burned and unburned hydrocarbons, carbon monoxide, oxides of nitrogen and sulfur, and traces of various acids, alcohols, and phenols, The crankcase is a secondary source of unburned hydrocarbons and, to a lesser extent, carbon monoxide. In the fuel tank and (in older automobiles) the carburetor, hydrocarbons that are continually evaporating from gasoline constitute a minor but not insignificant contributing factor in pollution.
A variety of systems for controlling emissions from all these sources have been developed. In the crankcase—the portion of the engine block below the cylinders where the crankshaft is located—leaked combustion gases are combined with ventilating air and returned to the intake manifold for reburning in the combustion chamber. More From Britannica automobile: Emission controls To control exhaust emissions, which are responsible for two-thirds of the total engine pollutants, two types of systems are used: the air-injection system and the exhaust gas recirculation (EGR) system.
In EGR a certain portion of exhaust gases are directed back to the cylinder head, where they are combined with the fuel-air mixture and enter the combustion chamber, The recirculated exhaust gases serve to lower the temperature of combustion, a condition that favours lower production of nitrogen oxides as combustion products (though at some loss of engine efficiency).
In a typical air-injection system, an engine-driven pump injects air into the exhaust manifold, where the air combines with unburned hydrocarbons and carbon monoxide at a high temperature and, in effect, continues the combustion process. In this way a large percentage of the pollutants that were formerly discharged through the exhaust system are burned (though with no additional generation of power).
Another area for additional combustion is the catalytic converter, consisting of an insulated chamber containing ceramic pellets or a ceramic honeycomb structure coated with a thin layer of metals such as platinum and palladium. As the exhaust gases are passed through the packed beads or the honeycomb, the metals act as catalysts to induce the hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust to convert to water vapour, carbon dioxide, and nitrogen.
These systems are not completely effective: during warm-up the temperatures are so low that emissions cannot be catalyzed. Preheating the catalytic converter is a possible solution to this problem; the high-voltage batteries in hybrid cars, for example, can provide enough power to heat up the converter very quickly.
- In the past, gasoline fumes evaporating from the fuel tank and carburetor were vented directly into the atmosphere.
- Today those emissions are greatly reduced by sealed fuel-tank caps and the so-called evaporative control system, the heart of which is a canister of activated charcoal capable of holding up to 35 percent of its own weight in fuel vapour.
In operation, fuel-tank vapours flow from the sealed fuel tank to a vapour separator, which returns raw fuel to the tank and channels fuel vapour through a purge valve to the canister. The canister acts as a storehouse; when the engine is running, the vapours are drawn by the resultant vacuum from the canister, through a filter, and into the combustion chamber, where they are burned. Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now This article was most recently revised and updated by Adam Augustyn,
Is catalytic converter part of MOT?
Your car might pass it’s MOT, but it might need some things replacing, such as the catalytic converter, fuel filter, and the air filter (if you have one).
Is emissions light an MOT failure?
Is an Illuminated Engine Management Light an MOT Fail? – If your engine management light comes on and stays on during an MOT test, this will be classed as a major fault, This is understandable, given that this likely means your car is unsafe, or is not as clean as it needs to be.