Drivers of vans and 4x4s are being warned to be on their guard following a spate of catalytic converter thefts.
Vehicles with a high ground clearance can be an easy target for thieves, who rip out the devices which contain precious metals, like platinum.
Police want owners to take extra care after another series of thefts in the area.
A catalytic converter was stolen from a vehicle in Minsmere Drive in Great Cornard between 7.30pm last Monday and 2.30pm the next day.
Two men were caught in Swan Street, Boxford, last Tuesday at 12.10am stealing a converter. They were shouted at but drove off.
On the same day in Alexandra Road, Sudbury, at around 8.15pm, a man was seen under a vehicle. He then got into a silver car, with another man, and drove off.