Thieves stole a catalytic converter from a Toyota car in the West Road area of Bridport sometime over the last week, police said.
Catalytic converter thefts are on the rise, due to the price of the precious metals inside and often Japanese models of vehicles are targeted, according to officers.
The parts are often removed by grinding them off.
A Dorset Police spokesman said: "Please be vigilant and report any suspicious activity to us on 101, or 999 if you believe a crime is in progress."
Catalytic converters form part of a car’s exhaust system. They contain a honeycomb coated with precious metals such as platinum, palladium and rhodium which help to reduce and filter harmful gases from the vehicles’ exhaust systems.
Cars that have had their converter stolen cannot be legally driven. Replacement catalytic converters can cost up to £1,000, which can be very costly for targeted motorists.
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