Catalytic converter (CAT) theft

Catalytic converters stolen for precious metals

Here's how you can protect your car

Vehicles, particularly those with large ground clearance may be at risk from thieves targeting catalysts – located in the exhaust system under the vehicle – because of the high value of the precious metals they contain.

  • When precious metal prices go up the demand for parts that contain them goes up too, and the risk of theft of catalytic converters increases.
  • On diesel cars, the diesel oxidation catalyst is often integrated with the Diesel Particulate Filter (DPF) and there is anecdotal evidence that these are being stolen for their scrap value too.
  • Catalytic converters (CATs) have been fitted in the exhaust of the majority of petrol cars manufactured since 1992 and diesel cars since 2001.


Shutterstock cat conv

By chemical reaction CATs substantially reduce harmful pollutants from the exhaust.

  • The metal case of the CAT contains a ceramic honeycombed structure providing a massive surface area across which the exhaust gases flow.
  • Precious metals – platinum, palladium and rhodium – are coated onto this ceramic structure as catalysts (a catalyst modifies and increases the rate of a chemical reaction without being consumed itself) for the reactions that 'clean' the exhaust:
    • Oxidising (adding oxygen) carbon monoxide and unburnt hydrocarbons to form carbon dioxide and water, and
    • Reducing (remove oxygen) from other gases such as oxides of nitrogen.


In recent years, catalytic converter theft has risen dramatically. AA insurance claims have gone up from 32 in 2018 to 393 in 2019. It is believed that this is driven by the value of the metals inside. While platinum prices have remained fairly stable, there has been a sharp increase in the value of palladium. 

Thieves simply cut the catalytic converter from the exhaust pipe of a parked car and sell them on to scrap metal dealers.

  • Taller vehicles (4x4s) are particularly vulnerable as the converters are more accessible. Because they tend to have larger engines, they contain more of the precious metals too.
  • Once an unmarked converter has been removed from a vehicle it's quite difficult to match it to that vehicle as there aren't any distinguishing marks.

Reduce risk

To reduce the risk of theft of your car's catalytic converter:

  • Garage your car whenever possible
  • Park in well-lit busy areas
  • Look out for people working under cars
  • If the car's high risk consider marking the metal shell of the converter with a unique mark, so that if it is removed by thieves it will be easier to trace back to your vehicle
  • If you operate a small fleet, consider obstructing access to vehicles with high ground clearance by parking lower vehicles close by.

11 March 2020

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