Motorists have been warned to be on the look-out for thieves tampering with vehicles following a spate of thefts in the past week.
A total of 18 vehicles across the county have had their catalytic converters stolen since Monday, February 10.
The devices are a section of a vehicle’s exhaust system which reduce carbon emissions into the environment and contain a number of valuable metals.
They can be removed from a vehicle in between 90 seconds and three minutes, but can cost more than £1,000 to replace.
Chief Inspector Tom Thompson said: “We know offenders tend to favour vehicles with high ground clearance, such as vans and 4x4 vehicles, but we also know that people carriers are vulnerable too.
“Our advice to drivers is to be aware of this type of theft and park their vehicles in garages if possible.
“They should also consider getting their catalytic converters professionally marked, as this helps to deter thefts.”
Catalytic converter thieves are known to strike at any time of the day.
The more organised thieves attack car dealerships, van rental lots, specialist repair garages, corporate fleet car parks and poorly attended car parks.
For more information call Northamptonshire Police on 101 and ask for your local Crime Prevention Officer or email CrimePrevention@northants.police.uk.