Thames Valley Police are 'intensifying' action to stop thieves stealing catalytic converters.
The number stolen is on the rise nationally due to an increase in price of the metals contained within them.
The force has been working with garages, visited scrap metal merchants with patrols in areas where vehicles have been targeted repeatedly.
Detective Superintendent Jim Weems, leading the operation for Thames Valley Police, said: "Catalytic converter theft is on the rise nationally as well as in the Thames Valley due to the increase in price for the precious metals contained within them.
"Offenders are organised in their execution of the crime and often steal a catalytic converter in minutes.
"This crime has a significant impact on victims who find themselves without their vehicle to get around and often have to join a waiting list to obtain a replacement."
Thames Valley Police tips on reducing risk of theft:
Protect your car by asking your dealer if they can give you any advice on locks or guards that are approved by the vehicle manufacturer and tested to Sold Secure Gold standard.
Mark your catalytic converter with a forensic marker and register your converter to make it harder for thieves to dispose of.
Park your car somewhere well-lit and overlooked, amongst as many cars as possible. Try to park so the converter can't be easily reached, such as close to a wall or fence.