Catalytic converter theft: risks and protection

A catalytic converter sits in the exhaust under the car and contains small amounts of precious metals. That is why thieves steal them: a converter can be cut out in minutes and sold on for its metal. If your car suddenly sounds like a tractor when you start it, check underneath, because a stolen converter is the most likely cause. You can make theft less likely with where you park, a marking kit and a guard. If one goes, the car should not be driven further than you need to, and missing emission control equipment is a major defect at the MOT.

What a catalytic converter does

A catalytic converter, often shortened to "cat", turns some of the harmful gases in the exhaust into less harmful ones. Inside is a honeycomb coated in metals that speed up those reactions. Petrol cars sold new in the UK have had one for decades, and most diesels have their own catalyst alongside the particulate filter.

Those coating metals, such as platinum, palladium and rhodium, are what make the part valuable to thieves. The car does not run better without it. It runs louder and dirtier, and should not be used on the road like that.

Which cars are targeted

Police crime prevention advice points to cars where the converter is easy to reach or worth more. In practice that tends to mean:

• vehicles that sit higher off the ground, such as SUVs and vans, because thieves can get under them without a jack;
• some hybrid cars, because the engine runs less of the time, so the converter is used less and is less likely to be corroded, which keeps the metals worth more;
• cars parked in quiet spots, in long-stay car parks or on the street overnight.

We do not name models. Any car with a catalytic converter can be a target, and where it is parked matters as well as what it is.

Signs your converter has been stolen

• A very loud exhaust when you start the engine, often a roar that gets louder as you rev.
• A rough or uneven engine, sometimes with the engine management light on.
• Fresh cuts in the exhaust pipe under the car, usually between the engine and the middle of the car.
• Exhaust smell inside the car.

If you think it has gone, do not drive the car further than you need to. Report the theft to the police on 101, or 999 if it is happening now, and call your insurer. Keep the crime reference number for the claim.

How to protect your car

Police forces give broadly the same advice. Combine as many of these as you can.

1. Park carefully. Use a locked garage if you have one. If not, park in a busy, well lit place, close to your home, with the exhaust side near a wall or fence so it is harder to reach.
2. Mark the converter. Forensic marking kits, or a serial number etched onto the converter by a garage, make it easier to identify if stolen and act as a deterrent.
3. Fit a guard or lock. Metal guards, cages and clamps make removal slower and noisier. If the converter is bolted on, a garage may be able to weld the bolts. Ask the manufacturer or a dealer what suits your car, and tell your insurer about the change.
4. Use an alarm that senses tilt. An alarm that goes off when the car is lifted or tilted can catch thieves in the act.
5. Report suspicious activity. Someone jacking up a car in a car park or on the street at night may be stealing its converter.

The law on selling scrap metal

The Scrap Metal Dealers Act 2013 made it harder to sell stolen metal. Dealers in England and Wales need a licence from the local council, and section 12 says a scrap metal dealer must not pay for scrap metal except by a non-transferable cheque or an electronic transfer of funds. If a dealer pays any other way, such as in cash, the dealer commits an offence, and so can the site manager and anyone who makes the payment for the dealer.

For an owner, the practical point is that a legitimate dealer has to keep records of who it buys from and pay by traceable means, so a marked converter is harder to sell on.

Insurance

Whether you are covered depends on your policy. Theft cover is usually part of a comprehensive policy and is not included in third party only cover. Check the wording for the excess and any conditions, ask what courtesy car cover you have, and bear in mind a claim can affect your premium.

The MOT and driving without a converter

A car with its catalytic converter missing will fail its MOT. The MOT inspection manual makes emission control equipment fitted by the manufacturer that is missing, obviously modified or obviously defective a major defect. Exhaust noise in excess of the permitted level is also a major defect, and the emissions test is likely to fail too. Our guide to the MOT emissions test explains those checks.

Driving with a missing converter also exposes everyone in the car to more fumes. Get it fixed before you use the car for normal driving.

When you are buying a used car

A past catalytic converter theft is not a reason to avoid a car on its own, as long as it was repaired properly. Ask:

• Has the converter ever been stolen or replaced? If so, ask for the invoice and whether the replacement was an original part or one made for that car.
• Is the exhaust quiet and the engine light off? A loud exhaust at a viewing needs an explanation.
• Does the MOT history show exhaust or emissions failures? Our guide to reading MOT history explains what to look for.
• Is there a guard or marking? If you are buying a car that thieves like, a guard already fitted is a plus.

For a hybrid, the converter is one thing to ask about and the battery is another. Our MOT pages show how often each model fails its MOT at each age, from DVSA's anonymised MOT test records. For anything that feels off, see the car and ask a mechanic.

Frequently asked questions

How do I know if my catalytic converter has been stolen?

The car will be much louder than usual when you start it, and it may run roughly. Look underneath for a missing section of exhaust with clean cut ends.

Can I drive without a catalytic converter?

You should not drive further than you need to, for example to a garage. The car will be noisy, it will put out more harmful exhaust and it will fail its MOT. Regulation 61A of the Construction and Use Regulations allows a car whose emission control equipment is not working to be driven to be repaired, but not used as normal.

Does insurance cover catalytic converter theft?

It depends on the policy. Theft cover usually comes with comprehensive cover, not third party only. Check the excess and any conditions in your policy wording.

Why are hybrid cars targeted for catalytic converters?

Police advice notes that the converter on a hybrid is used less, because the engine runs less of the time, so its metals are less likely to corrode and are worth more.

Is it illegal to buy scrap metal for cash?

Yes, for a scrap metal dealer. Section 12 of the Scrap Metal Dealers Act 2013 says dealers must pay by a non-transferable cheque or electronic transfer.