How much does a catalytic converter replacement cost?

A catalytic converter replacement can produce one of the larger bills a garage will quote you, and the figure can look alarming at first glance. The reason there is no single price is that so much depends on your car, on whether you fit an original dealer part or a quality aftermarket one, and on the garage you choose. This guide sets out realistic UK ranges and explains what you are actually paying for, so you can judge whether a quote is fair.

What a catalytic converter actually does

The catalytic converter sits in the exhaust system, between the engine and the back box. Its job is to clean up the harmful gases your engine produces before they leave the tailpipe. Inside is a honeycomb structure coated with precious metals, and as hot exhaust gas passes through, a chemical reaction turns much of the harmful content into less harmful gas.

Because it is part of how your car meets its emissions rules, a healthy converter is not optional. If it stops doing its job, the car will usually fail the emissions section of the MOT, and it may run poorly in the meantime.

Signs your catalytic converter is failing

A failing converter tends to show itself in a few common ways. The engine management light may come on, since the sensors either side of the converter report that it is no longer cleaning the gases properly. If that light appears, our guide to why your engine management light is on explains what to check and when to act.

You might also hear a rattle from underneath, especially when you start up or accelerate. That rattle is often the internal honeycomb breaking apart and moving around inside the casing. Other signs include a noticeable loss of power, poorer fuel economy, and a sulphur or rotten egg smell from the exhaust. The clearest sign of all is a failed MOT on emissions, which is where many drivers first discover there is a problem.

Why catalytic converters are so expensive

The cost surprises a lot of drivers, and the main reason is what sits inside. The honeycomb is coated with precious metals, chiefly platinum, palladium and rhodium. These are genuinely valuable commodities traded on world markets, and at times palladium and rhodium have been worth more per gram than gold. When the price of those metals rises, the price of the part rises with it, which is why quotes can differ from one year to the next.

On top of the raw material, the part has to be matched precisely to your engine to meet the correct emissions standard, and larger engines simply need larger converters holding more of that costly coating. That is why a small hatchback and a big SUV can be quoted such different figures for what sounds like the same job.

Original dealer part or aftermarket?

One of the biggest choices you will make is between an original part from the dealer and a quality aftermarket one. An original part is built to your car maker’s exact specification and tends to be the most expensive option, often running well past £1,000 on larger or premium cars. A good aftermarket converter that is type approved for your vehicle can cost considerably less while still meeting the required emissions standard.

For many everyday cars, a quality aftermarket part is a perfectly sensible and legal choice. The important thing is that it is the correct part for your specific car and carries the right approval, so it will pass the MOT and keep the car running properly. A trustworthy garage will confirm exactly which part it is fitting and why.

How much does a catalytic converter cost? A quick reference

Treat these as starting points rather than fixed prices, because the make, model, engine size and your chosen garage all move the figure. The only way to know your number is a quote against your registration. If a converter fails, the garage will often check the rest of the exhaust at the same time, so it can be worth reading our guide on exhaust replacement costs too.

Catalytic converter theft

There is one more reason drivers end up needing a replacement, and it is not wear at all. Because of the precious metals inside, catalytic converters are a target for thieves, who can cut one out from underneath a parked car in minutes. Hybrids and some higher riding vehicles have been particularly targeted, partly because their converters can be richer in precious metals and partly because they are easier to reach.

If your converter is stolen, replacing it is exactly the same job and cost as replacing a worn one, and it is worth checking whether your insurance covers it. To reduce the risk, you can ask a garage or specialist about fitting a protective cage or guard, or having the converter marked so it is harder to sell on. Parking in a garage or a well lit, busy spot also helps.

Getting a fair written quote

Before agreeing to any work, ask for an itemised written quote that shows the part and the labour separately, and ask which type of converter is being fitted. That lets you compare like for like between garages and understand what you are paying for. Because this is an emissions related part, the cheapest quote is not always the right one, so quality and the correct approval matter more than shaving off a few pounds. If you want a wider steer on picking somewhere you can trust, see our guide on how to choose a good garage. Once you know roughly what the job should cost, you are in a strong position to book with confidence.