A catalytic converter replacement is not cheap. It costs between £150 and £800 on average in the UK. For some high-end vehicles, it can even cost over £1000!

However, it is important, and you shouldn't ignore the need for one. Your catalytic converter (or 'cat' for short) reduces exhaust emissions. This, in turn, helps to reduce the issue of urban pollution, which can be detrimental to human health. Without the use of catalytic converters, there would be increased health risks and a deterioration in air quality.

By the end of this article, you will understand:

  • Why your catalytic converter costs as much as it does
  • What a 'cat' does
  • What it looks like
  • Why every car needs a catalytic converter
  • When to book a replacement



A catalytic converter can cost between £150 and £800 for the average UK driver. This is because it contains Platinum, Rhodium or Palladium (three rare precious metals). This value also makes it a lucrative target for thieves who sometimes steal catalytic converters in broad daylight!

These thefts are bad in many ways, especially for the environment. A catalytic converter reduces your exhaust emissions, CO2 (Carbon Dioxide) in particular. This helps to make your car as environmentally friendly as possible.

If you look under the back of your car and you can't see your 'cat', you see a warning light or you notice any of the many warning signs of failure, you must book a replacement as soon as possible.

Fortunately, your 'cat' should last between 70,000 and 100,000 miles, depending on your driving style and other external factors. This means you may never have to deal with a repair in your driving life.


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How Much Does a Catalytic Converter Cost? 

The average UK catalytic converter replacement cost is between £150 and £800. It can even cost over £1,000 for some high-end vehicles! The price of a catalytic converter may seem expensive, but an inefficient part can cost a lot more.

As with many car repairs, the cost does depend on what type of vehicle you drive.

The average replacement cost for three types of vehicles are as follows:

  • City cars & Hatchbacks - £150 - £250
  • Saloons & Estate Cars - £300 -£400
  • Sports & Deluxe Cars - £500+

You can browse replacement parts on Eurocarparts to get an idea of the current prices for your vehicle.


Why Does a Catalytic Converter Cost So Much?

Catalytic converters are not cheap to build. They use Platinum, Palladium or Rhodium as a catalyst. These precious metals are hard to find and cost between £28 and £570 per gram!

And, as these prices constantly fluctuate, it's hard to predict how much a catalytic converter will cost.

Since replacing a catalytic converter can be such a big job, you may end up paying higher labour costs. The car needs to be lifted off the floor, and if the converter is welded or bolted to the car the mechanic may need to use specialist tools.

If you're looking for a quote for your catalytic converter replacement, don't accept any offer until you've done so. We'll help you find the best deal in your area.

Once the garage has had a look, they will provide a transparent, no-obligation price for a new catalytic converter from a garage near you. Most importantly, you deal with the garage directly and you never pay a penny until after they have completed all the work.


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What Does a Catalytic Converter Do?

The catalytic converter speeds up the removal of harmful exhaust gases. It does this by splitting their molecules up before they can leave the exhaust. It converts CO2 (Carbon Dioxide) and NOx (Nitrogen Oxides) into Oxygen and water vapour.

These are much cleaner emissions, which are much safer to release into the atmosphere.

CO2 contains carbon and oxygen and NOx contains nitrogen and oxygen. These molecules are bonded together through chemical reactions during the combustion process.

Each of these elements is less harmful on its own, so modern exhaust systems are designed to release them into the atmosphere separately.


Does My Car Need a Catalytic Converter?

Yes, your car needs a catalytic converter. Every car registered in the UK must have one fitted by law. It has been standard for petrol vehicles since 1992, and 2001 for diesel vehicles.

Petrol and diesel engines combust differently, so there are different types of catalytic converters.


'Two-Way Oxidation' - The first versions had a simple purpose. They turned Carbon Monoxide into CO2, and Hydrocarbons (particles of unburned fuel) into CO2 and water.

'Three-Way-Oxidation' - This type of catalytic converter is fitted to modern cars. It has the same purpose as 'Two-Way Oxidation' but reduces your NOx emissions as well. These include Nitric Oxide (NO) and Nitrogen Dioxide (NO2. These are two of the most harmful exhaust emissions.

'Diesel Oxidation Catalyst' - These units are fitted to diesel vehicles. Diesel cars naturally produce more pollution than petrol cars. Without any intervention, this would choke the planet. To combat rising pollution levels, car companies invented several other exhaust treatments which include Diesel Particulate Filters and AdBlue.


Modern catalytic converters are more efficient than the original models. This means that our cars release less CO2 into the environment now than ever before - even if they can't reduce it to 0%.


What Does a Catalytic Converter Look Like?

A catalytic converter looks like a large metal box with two pipes coming out of it. This is bolted to the exhaust assembly underneath the back of your car (as below).


zoomed in image of a catalytic converter on the underside of a vehicle

If you can't see your 'cat', you should get your car towed to a local garage immediately. You've likely been the victim of a catalytic converter theft, which is becoming an ever-growing problem in the UK.


Why Are Catalytic Converter Thefts So Common?

'Cat' thefts are increasingly common in the UK because the catalyst materials have a very high value. As well as this, the part is an easy target.

Thieves don't need to be delicate when stealing a 'cat'. They can quickly cut the entire exhaust manifold away from the car and disassemble it later. This means many thefts happen in broad daylight.

If you suspect you've been the victim of a catalytic converter theft, don't drive the car. Get a second opinion from your recovery provider or a local mechanic and then contact the police to report the crime. You will also need to source a replacement catalytic converter.

Fortunately, if you can provide a valid crime number to your insurance company, they should cover the cost of the replacement for you.

A mechanic near you will be happy to look at your car and tell you whether or not your catalytic converter has been stolen and needs replacing.


What Can Cause Your Catalytic Converter To Wear Out?

Like most aspects of your vehicle, treating your car in a certain way can influence the lifespan of your catalytic converter. There are several things that could cause your catalytic converter to need changing sooner than expected.


  1. Poor Engine Maintenance.

If your engine is in poor shape, your converter will wear out quickly. Things such as worn-out valve guides, misfiring spark plugs, and incorrect oils and fuels can contribute to shortening the lifespan of your catalytic converter.


  1. Coolant Leaks

If your antifreeze or coolant leaks into the combustion chamber you could end up with a large problem on your hands. The leak will clog the converter, which will lead to the production of thick soot.

This soot blocks the air passages, rendering the converter useless.


  1. Only Using Your Car For Short Trips

The catalytic converter only works when it reaches a certain temperature – if it doesn’t get hot enough it will not burn hydrocarbons completely. It takes your car time to reach this temperature, so if you’re only driving for five minutes at a time you will end up with a clog.

Go for a longer drive regularly to ensure the burning of the build-up of deposits in the converter.


  1. Broken Oxygen Sensor

If your oxygen sensor is malfunctioning, it may be sending inaccurate readings to your car’s computer. This can result in issues with the conversion of harmful fumes to safe ones.


  1. Broken Spark Plugs

If your spark plugs are misfiring it could result in unburned fuel igniting inside the converter. This will melt the ceramic to melt and malfunction.


When Do I Need to Book a Catalytic Converter Replacement?

If there is a problem with your 'cat', you need to get it sorted right away.

Fortunately, it gives you plenty of warning if there is a problem. The most common of which would be seeing either of these warning lights.


Engine warning light and catalytic converter warning light

Your catalytic converter warning light is on the left, and your engine management light is on the right.


If either warning light comes on, you should book an inspection at a garage near you. You should always take a warning light seriously, but it's even more important if you see the exhaust warning light.

It could lead to an MOT failure and a very expensive repair bill if you don't get the problem fixed.

Almost 1.3 million drivers failed an MOT due to excess exhaust emissions in 2020 - don't let it be you in 2023.

Even if you don't yet see the warning light, any of these symptoms could mean your catalytic converter has a problem.

  • Your engine runs rough
  • Increased fuel consumption
  • Increased emissions
  • Excessive white smoke
  • Blue smoke
  • Slower acceleration
  • The engine does not accelerate past a certain RPM (usually idle speed)
  • Your engine cuts out (due to additional backpressure)
  • There is a rattling noise from the exhaust

By catching an exhaust problem early, you can preserve your catalytic converter and increase your chances of passing the MOT emissions test.

It may also help to keep the cost of your replacement down.


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How Long Does a Catalytic Converter Last?

A catalytic converter should last between 70,000 and 100,000 miles.

However, like most car parts, the lifespan of your 'cat' is affected by your driving habits. Lots of stop-start or short journeys can wear it out quicker.

This is because they don't bring the car up to the proper running temperature.


How Long Does it Take to Replace a Catalytic Converter?

A catalytic converter replacement takes about 1-2 hours on average. It's fairly easy to access so the mechanic doesn't have to disassemble your car to remove the old one. This saves you a lot of time!


We hope that you have enjoyed learning about the cost of catalytic converters in 2023. If you would like to learn more about car costs, why not find out how much car brake pads and discs cost?