Because of the external location and the use of valuable precious metals including platinum, palladium and rhodium, catalytic converters are a target for thieves. The problem is especially common among late-model trucks and SUVs, because of their high ground clearance and easily removed bolt-on catalytic converters. Welded-on converters are also at risk of theft, as they can be easily cut off. Pipecutters are often used to quietly remove the converter but other tools such as a portable reciprocating saw can damage other components of the car, such as the alternator, wiring or fuel lines, with potentially dangerous consequences. Rising metal prices in the U.S. during the 2000s commodities boom led to a significant increase in converter theft. A catalytic converter can cost more than $1,000 to replace, more if the vehicle is damaged during the theft.

From 2019–2020, thieves in the United Kingdom were targeting older-model hybrid cars which have more precious metals than newer vehicles—sometimes worth more than the value of the car—leading to scarcity and long delays in replacing them.

In 2021 a trend emerged in the Democratic Republic of Congo where catalytic converters were stolen for use in drug production.