How much does a catalytic converter replacement cost?

UK catalytic converter replacement costs at a glance

Prices include parts and labour unless noted. Typical market observations as of 2025. Always get a current quote.

The cost of the cat itself varies significantly by vehicle make and model. Luxury and performance vehicles often need expensive OEM units. Always confirm the part specification before accepting a quote.

Average catalytic converter prices by UK city

Typical range for a standard petrol cat replacement at an independent garage, parts and labour included.

Prices are approximate market observations as of 2025. Always get a current quote.

Cat vs DPF: make sure you are fixing the right part

These two exhaust components are confused regularly and the mistake is expensive. A catalytic converter converts toxic gases chemically. A diesel particulate filter physically traps soot. Diesel vehicles have both; petrol vehicles typically only have a cat.

If you have a diesel and the garage recommends a catalytic converter replacement, ask them to confirm via a fault code read whether it is the cat or the DPF (or both) that is failing. A DPF clean is typically £100 to £200 and is very different from a £400 cat replacement.

See our separate guide on how much a DPF clean costs for diesel-specific advice.

How to get a fair price for a catalytic converter replacement

1. 1. Confirm via a diagnostic scan that the cat is the failing component and not an oxygen sensor or DPF issue causing similar symptoms.
2. 2. Ask the garage to specify the replacement part: OBD-approved, emission-standard-matched, and warranted for at least 12 months.
3. 3. If the cat failed due to an engine fault (misfires, oil burning), fix that fault first: a new cat fitted to a poorly running engine will fail quickly.
4. 4. Get at least two quotes, especially for theft replacements where urgency can lead to overpaying.
5. 5. If the cat was stolen, get a crime reference number from the police before having it replaced: your insurer will need it.

AutoFixFair lets you post your exhaust or emissions job and get competing quotes from local garages in Manchester, London, Birmingham, and other UK cities.

Common questions about catalytic converter replacement costs

What does a catalytic converter do?

A catalytic converter is part of your exhaust system. It uses precious metals (typically platinum, palladium, and rhodium) to convert harmful combustion gases, specifically carbon monoxide, hydrocarbons, and nitrogen oxides, into less harmful carbon dioxide, water, and nitrogen before they exit the tailpipe. A failed or missing cat causes higher emissions, engine warning lights, and an MOT failure.

What is the difference between a catalytic converter and a DPF?

A catalytic converter (cat) is found on both petrol and diesel vehicles and converts toxic gases. A diesel particulate filter (DPF) is a separate device found on diesel cars that physically traps soot particles from the exhaust. Diesel vehicles typically have both. They fail in different ways: cats fail chemically (poisoning, overheating, physical damage) while DPFs block with soot. A DPF clean or regeneration is a different job from a cat replacement. Confirm with your garage which component has failed before authorising work.

Why are catalytic converters stolen so often?

Catalytic converters contain platinum, palladium, and rhodium, which are extremely valuable metals. Thieves can remove a cat in under two minutes with an angle grinder. Hybrid vehicles such as the Toyota Prius are particularly targeted because their cats are used less and retain higher concentrations of precious metals. If your cat is stolen, you will typically hear a loud roaring exhaust noise immediately when you start the engine. Report it to the police and your insurer before getting it replaced.

Will a failed catalytic converter cause an MOT failure?

Yes. Emissions are tested as part of the MOT. A failed, damaged, or missing catalytic converter will cause your vehicle to exceed the permitted emissions limits and fail the test. In some cases a warning light (typically the engine management or lambda sensor light) will also trigger a fail. Do not attempt to remap or disable the emissions system to pass the MOT: this is illegal and will result in a permanent MOT failure if detected.

Can I drive with a failing catalytic converter?

You can usually continue driving in the short term, but you should not delay repair. A partially blocked or cracked cat reduces engine performance and fuel economy, and a shattered ceramic substrate can cause debris to travel further down the exhaust system. An engine running without a functioning cat (or with one that has been stolen) is illegal on public roads and will not pass an MOT.

What causes a catalytic converter to fail?

The most common causes are: physical damage from road debris or a low-speed impact; overheating caused by a rich-running engine (often a failing oxygen sensor or ignition fault); oil or coolant contamination from internal engine burning; and simply age and high mileage. Theft is a significant cause in urban areas. Addressing the root cause (such as fixing an ignition misfire) is important when replacing a cat: fitting a new cat to an engine with an unresolved fault will destroy the replacement quickly.

Does it matter which catalytic converter replacement I use?

Yes. Replacement cats must meet the Euro emissions standard your vehicle was manufactured to. An undersized or non-type-approved unit may fail the MOT emissions test even if it looks and fits correctly. Ask your garage to fit an OBD-approved (OBD2-compliant) replacement cat that matches your vehicle specification. Avoid the cheapest universal-fit units: they often fail the MOT emissions check and need replacing again within months.

How can I protect my catalytic converter from theft?

Options include a cat cage or shield (a welded steel cage bolted around the cat, typically £150 to £300 fitted); a cat alarm (a vibration sensor that triggers the car alarm if the cat is tampered with); and marking your cat with a forensic marking solution and displaying a visible deterrent sticker. Parking in well-lit, busy areas or in a locked garage reduces risk. Some insurance policies now include cat theft cover: check your policy or ask your insurer.

Is catalytic converter replacement covered by insurance?

Cat theft is typically covered under comprehensive car insurance as it is treated as theft of a vehicle component. You will usually pay your policy excess and may lose your no-claims discount. Some insurers have introduced specific cat theft riders. Emission failure due to age or wear is not an insurance matter and is a repair cost. Always report theft to the police first and obtain a reference number for your insurer.