Whether you're warming up your vehicle on a cold morning or leaving your vehicle running outside of a store for a quick trip inside, it is illegal in Maryland to leave an unattended motor vehicle with its engine running.
An unattended running vehicle is an open invitation to car thieves. Don't give them the opportunity.
Sec. 21-1101 of Maryland's Vehicle Laws states, "a person driving or otherwise in charge of a motor vehicle may not leave it unattended until the engine is stopped, the ignition locked, the key removed, and the brake effectively set."
Regarding newer vehicles and keyless ignition systems, the law does not apply to a person who "is in charge of a motor vehicle that has had the engine started using a remote keyless ignition system and has been operating unattended for up to 5 consecutive minutes when the vehicle is not in motion; or allows a motor vehicle that is locked and is on private property not open to the public to operate unattended for up to 5 consecutive minutes when the vehicle is not in motion."
The fines for violation are $70 and one point assessed on a driver's license or $110 and three points if contributing to an accident.