The catalytic converter is located beneath the car and helps to keep toxic emissions out of the environment. The car part is made from precious metals such as platinum and rhodium. These materials have increased in value over recent months, making the catalytic converter a popular choice for thieves who can sell it for scrap metal to recycling yards, says Ward. He says the cost to replace the part is about $1,000, including parts and labor, and possibly up to $2,000 if thieves cause substantial damage to the exhaust system.

He says likely targets for catalytic converter theft are vehicles that sit high off the ground, such as SUVs and pickup trucks. "An experienced thief can cut one off in two minutes," he says. "And as a result, it compromises the car's entire exhaust system."

Ward says that a car owner can tell when his catalytic converter is missing. When he starts the car, "it sounds like a loud, bad truck," instead of a car's normal hum.

Fortunately, laws have recently passed in many states to deter thieves from selling the car parts, says Calkins. Under these regulations, if a salvage yard or recycling center buys a used catalytic converter, it has to document the seller's identity, he says.