Police are reminding people in Ilkley to keep their vehicles locked and remove any valuables before leaving them unattended, following the theft of a purse and satellite navigation system.
The warning comes after suspects targeted an insecure MG car in Ben Rhydding overnight on Monday, June 2.
Officers later arrested a 17-year-old from Leeds, on Leeds Road, on suspicion of theft from a motor vehicle.
He has since been released on bail.
Inspector Sue Sanderson, who leads the Keighley Area Neighbourhood Team, said: "We urge people to check their cars to make sure they do not leave them unlocked or insecure.
"Experience suggests opportunist thieves will simply move along if they find a car has been secured, so taking a few seconds to make sure your vehicle is safe really will reduce your chances of being a victim of crime.
"If you have a car with central locking, make sure you press the fob or use the key to ensure it is secure, before leaving it unattended."
She added: "We also advise people to remove valuables from their vehicle when leaving it unattended, as leaving these items in view is inviting a thief to take them."
Visit westyorkshire.police.uk/crimeprevention or call your local Neighbourhood Policing Team on 101 for crime prevention help and advice.