How does a catalytic converter work?
A catalytic converter is a part of your car's exhaust system that helps reduce pollution. It looks similar to a silencer. When the engine burns fuel, it creates exhaust gases that can be harmful to the environment. As these gases pass through the catalytic converter, they flow over special materials like platinum, palladium, and rhodium inside it.
These materials cause a chemical reaction that changes the harmful gases, like carbon monoxide, nitrogen oxides, and hydrocarbons, into less harmful ones, such as carbon dioxide and water vapour. This process significantly reduces the amount of pollution your car emits.
In simple terms, a catalytic converter cleans up the exhaust gases from your engine, making them less harmful to the environment before they leave your car’s exhaust system. Without a catalytic converter, your car will fail the MOT test!
Why are catalytic converters being stolen?
In 2019, there were nearly 13,000 recorded thefts of catalytic converters in the UK, with a large proportion of these being in London. Between 2021 and 2023, just under 19,000+ catalytic converters were stolen in London alone. And sadly, these figures will no doubt continue to rise.
Catalytic converters contain three important precious metals, rhodium, platinum and palladium and the prices of these metals have increased hand over fist in recent times, with palladium being worth more than gold, weight for weight.
The catalytic converters are being removed from cars and sold to unlicensed scrap metal dealers for big sums of money and once sold, the parts are untraceable.
What does a catalytic converter replacement job involve?
Replacing a catalytic converter, especially due to stolen parts, is becoming a routine repair for all mechanics and can be done both kerbside as well as in the workshop, providing it is safe to do so.
Whilst there are variations between manufacturers, the basics are pretty similar.
The mechanic will;
* Raise the vehicle
* Inspect the area from where the catalytic converter was positioned for any further damage
* Remove any remaining, yet, damaged sections
* Install the new exhaust sensors into the catalytic converter and fit it to the vehicle
* Plug in the exhaust sensors to the wiring loom and ensure everything is secure
* Start the vehicle and ensure there are no exhaust gas leaks and clear any error codes that were created by the theft
How do I know whether I need a catalytic converter repair or replacement?
If your catalytic converter has been stolen, you will need a replacement. Signs of theft include a loud exhaust noise and rough driving due to the missing converter. It’s crucial to replace the stolen converter promptly to restore your vehicle’s performance and compliance with emissions regulations.
* Check Engine Light: If your check engine light comes on, it could indicate a problem with the catalytic converter. The vehicle’s diagnostic system can detect issues with the converter and trigger this warning.
* Poor Engine Performance: If you notice a significant drop in engine performance, such as reduced power, acceleration, or fuel efficiency, it could be due to a clogged or failing catalytic converter. This happens because the converter is not processing exhaust gases efficiently.
* Rattling Noise: If you hear a rattling noise from underneath the car, especially during startup or acceleration, it might mean the catalytic converter is damaged internally. This noise usually indicates that the internal components are breaking apart.
Increased Emissions: If your vehicle fails an emissions test or you notice a strong sulfuric or rotten egg smell from the exhaust, it’s a sign that the catalytic converter isn’t functioning properly. A failing converter can’t effectively reduce harmful emissions.
* Reduced Fuel Efficiency: If you observe a sudden drop in fuel efficiency, it could be due to a problem with the catalytic converter. A clogged converter can cause the engine to work harder, thus consuming more fuel.
What other repairs do I need to replace a stolen catalytic converter?
Unfortunately, not only do the thieves make off with your catalytic converter, the all important exhaust gas sensors (Labda or O2 sensors) are usually screwed into the unit and therefore the wires to them are cut and they are made off with as well.
We can advise on the most likely scenario of what has been taken and what therefore needs to be replaced. Obviously, we do not know what other damage has been done by the thieves in order to remove the part, but generally, they use the quickest method which is to cut the section out, so minimal other damage is made.
In some cases, we do not know for certain what further damage there is that will require parts. Once the mechanic is on site, they can quickly review the situation and discuss with you what is going to be required over and above what was quoted.
Are certain cars vulnerable to catalytic converter theft?
There is one car in particular that is the easiest target of all and that is the Honda Jazz. It can take less than 5 minutes from pulling up alongside the vehicle, to be away with the part, some professional thieves take even less time.
At ClickMechanic, vehicles we get a lot of enquiries for are the Toyota Prius, Honda CR-V and Lexust RX range.
Can you protect my new catalytic converter from being stolen?
There are a number of devices on the market that claim to deter thieves from stealing the part. However, any determined thief is likely to be unhindered by them and may cause even more damage in order to steal the part.
If you wish to have such a device fitted, you will need to purchase it yourself and then inform us that you wish to have it fitted. We can then discuss this with the mechanic and they usually can fit it as part of the replacement for you.
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Frequently asked questions about catalytic converter replacement & repairs
Read our answers to questions about catalytic converter replacement costs, symptoms and more.
What does a Catalytic Converter do?
The catalytic converter, also called ‘cat’ sits next to your engine and is the key car part of the exhaust system, responsible for reducing the toxic emissions your engine produces into less harmful pollutants. Through a chemical reaction, the toxic emissions of hydrocarbons, carbon monoxide, and nitrogen oxides are turned into less harmful gases before they get emitted via the exhaust.
The core of a catalytic converter is made of ceramic blocks which have a porous structure. These pores are coated with catalysts containing valuable metals platinum, rhodium and palladium, which work best when heated up, hence the location next to the engine. During a drive, the toxic exhaust gases passing through the heated pores, causing a chemical reaction and are broken down into less harmful substances.
What does a catalytic converter replacement involve?
- Mechanic will read the ECU for catalytic converter and oxygen sensor related problems.
- Mechanic will inspect the catalytic converter for damage.
- Mechanic removes oxygen sensor for further check and removal of catalytic converter.
- If necessary, the catalytic converter will be replaced.
- Mechanic will advise if other parts need to be replaced.
- Mechanic will run engine, check catalytic converter operation.
- Mechanic will make adjustments where necessary.
Can I replace a catalytic coverter myself?
Unless you are a qualified mechanic with the required skills, training and equipment to do the job, we strongly recommend a catalytic converter replacement is only carried out by a professional mechanic. ClickMechanic can help get you a vetted and local mechanic to carry out the work. Just enter your postcode and your car's registration number at the top of this page and select the work needed to get an instant fixed price up front.
What are the symptoms of a bad catalytic converter?
You'll know something might be wrong with your car's catalytic converter:
- When dark smoke is coming from the exhaust
- When the engine performance is significantly reduced
- When fuel efficiency is decreasing
- When you experience issues while accelerating
- When the smell of sulfur (rotten eggs) is coming from your car
- When the check engine light flashes up
How long does it take to replace a catalytic converter?
On average, catalytic converter replacement times can range from just over 1 hour to 1.7 hours with an average of around 1.2 hours. The time that the job takes will depend on a number of factors, like your vehicle's make and model, year, as well as other factors. Select your car at the top of this page for information on job time and cost for your vehicle through ClickMechanic.
Is a bad catalytic converter an MOT failure?
If the catalytic converter is faulty and emits toxic pollutants above the legal limits then normally the car will fail its MOT.
How often should I replace the catalytic converter?
Catalytic converters are built to have a long lifetime, however over time the pores can become clogged, or overheating can cause physical damage. A damaged catalytic converter will emit more toxic pollution into the atmosphere. It is important to ensure the catalytic converter is always serviced as and when stipulated in the guidelines set out by your car's manufacturer.
What happens if I don't replace my catalytic converter?
If the catalytic converter stopped working as it should, your car will emit more toxic pollutants, likely above the legal limits. Cars which are passing exhaust fumes above these limits will fail their MOT.
A bad catalytic converter will certainly have an impact on other parts of your car, starting with the engine which is prevented from running freely. As a result, you will need to burn more and more fuel to power your engine appropriately up to a point where your car becomes undrivable.
Another impact of a bad catalytic converter can be overheating which causes damage to parts around it.
How to protect your Catalytic Converter from theft
There are ways to prevent the theft of your catalytic converter, mainly by making it harder to access and remove it. Below are a few suggestions on how to deter thieves or at least slow them down:
- Parking closer to walls, other vehicles or close to the kerb, to make climbing under your car more difficult.
- Marking the catalytic converter with an engraved serial number can allow easier tracing as well making it harder to sell
- Welding the bolts if the converter is bolted on. This does not stop thieves but makes it harder to remove the converter using only a spanner. The downside to consider is that it not only makes it harder for thieves but also mechanics when they are working on your exhaust system.
- Get a protective cover fitted to make it more difficult for thieves to remove the converter
- Get a catalytic converter alarm which is set off when the catalytic converter is tampered with
- Increased security measures, e.g. if possible park in a lockable garage, fencing, park in well-lit areas or CCTV ?
Why does catalytic converter theft happen?
Catalytic converters contain valuable and expensive metals, palladium and platinum, which makes them a target for theft. As the price for these metals increases the numbers of catalytic converter theft go up as well.
As part of the exhaust system, they are relatively easy to access, especially in taller vehicles which are further off the ground.
Catalytic converter theft not only leaves you with the cost of replacing it, but you will also need to take care of any other damages that are caused by the act of removal.
Can you drive a car with a bad catalytic converter?
A car with a bad catalytic converter will produce higher emissions, and will very likely fail an emissions test when tested. Another consideration is that knowingly using a vehicle on a public highway that would fail the emissions test is punishable by law (the police can stop you, test this and fine you). If you suspect there is any issue with your catalytic converter or there are concerns about its age or condition, book an inspection with a professional mechanic immediate effect.
Is catalytic converter checked during an MOT test?
Yes, the catalytic converter will be checked along with other parts of the exhaust emissions system. Depending on the age and fuel type of the vehicle, it will be checked that it meets all the rules regulations in regards to the relevant emission standards.
What causes the catalytic converter to fail?
There are 3 common causes for a catalytic converter failure:
* Excessive heat - misfiring spark plugs or even a leaky exhaust could cause unburned fuel to get into the catalytic converter
* Chemical contamination - including fluids such as oil and coolant, which can leak into the exhaust from the engine
* Physical or structural damage - going over speed bumps or damaged cause by high kerbs
What is the average lifespan of a catalytic converter?
Catalytics converters usually last 100,000 miles or even the entire lifetime of the vehicle, however this can differ depending on how and where you drive, and other internal and external factors.
Is it ok to drive with a broken or missing catalytic converter?
It is illegal to drive with a broken or missing catalytic converter in the UK, and could also lead to a hefty fine if caught by the police. It will furthermore lead to your vehicle failing its next MOT.
Additionally, driving without a catalytic converter can also lead to further damage to the engine and harmful emissions that are detrimental to the environment.
What happens if I don't fix or replace catalytic converter?
The engine, exhaust manifold, and underbody of your car can all be damaged if your catalytic converter is clogged and not replaced or fixed. When the catalytic converter is blocked, excessive heat and backpressure will be generated in the tailpipe, causing damage to the surrounding areas and affecting engine performance.
How much does replacing a catalytic converter cost?
A catalytic converter replacement generally costs between £175 and £500 with an average price of £310. Ultimately, the cost depends on your location, car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having your catalytic converter replaced by ClickMechanic by selecting your car at the top of this page!
Check out the ClickMechanic price for a catalytic converter replacement. See the averages for different makes below. We consolidate industry standard data with millions of data points to give you the most accurate price. These estimates may include Clamps and paste and Catalytic converter.
Name | Average Cost | |
---|---|---|
Audi | £1150 | Get exact price |
BMW | £774 | Get exact price |
Citroen | £503 | Get exact price |
Ford | £582 | Get exact price |
Land Rover | £1284 | Get exact price |
Mercedes-Benz | £1183 | Get exact price |
Nissan | £723 | Get exact price |
Peugeot | £443 | Get exact price |
Renault | £626 | Get exact price |
Toyota | £599 | Get exact price |
Vauxhall | £655 | Get exact price |
Volkswagen | £639 | Get exact price |
Estimates on average repair costs, such as the above results for a catalytic converter replacement, are based on ClickMechanic's quote data which combines multiple third-party sources. Actual costs may vary. We provide estimates on average repair costs for information only and accept no liability for any inaccuracies or errors. If you think an estimate is incorrect, please contact us to let us know.
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Mechanics that undertake catalytic converter work
- Automotive Vehicle Repairs, Sandbach
- Boni's, Sunbury-On-Thames
- CORNERWAYS GARAGE, Bedforshire
- CS Automotive, Buntingford
- Dans Mobile Motor Repairs, Watford
- Hammond's Autos, Upminster
- Hawkeye Performance LTD, Hoddesdon
- Kent Mechanics & Tyres, Ulcombe
- M L Autos, Thirsk
- Mmac Auto Repairs, Armagh
- Mobile Auto Services, Almondbank
- Mobile Tyre Tech, Glasgow
- RC Mobile Vehicle Servicing, Wokingham
- Rd Auto Repairs, Belfast Bt127bn
- S P Motors, Dundry
- SLG Autoserve Ltd, Kidlington
- T&G Autos, Birmingham
- T-Lane Pitstop Ltd, London