There is a law in Texas against leaving your keys in the ignition of your vehicle and thus you could be penalized for doing so.
The Texas Department of Motor Vehicles (DMV) notes on its site that not only is it illegal to leave your keys in your unattended vehicle, but if your vehicle is stolen with the keys in it, your insurance company may not cover your loss.
The law they are citing is under Section 545.404 of the Texas Transportation Code, “Unattended Motor Vehicle.” It states that a driver may not leave the vehicle unattended without:
1) Stopping the engine
(2) Locking the ignition
(3) Removing the key from the ignition
(4) Setting the parking brake effectively
(5) If standing on a grade, turn the front wheels to the curb or side of the highway.
Fines for leaving your car running
The Dallas Police Department notes that unattended vehicles with keys in the ignition can be cited with a fine typically under $200.
While Texas Transportation Code Section 545.404 prohibits drivers from leaving their car unattended without stopping the engine, locking the ignition, and removing the key from the ignition, the Texas court has held that this law only applies to vehicles parked on public highways and streets. The cities of Dallas, Austin and Arlington have also interpreted Texas Transportation Code Section 545.404 similarly.
Many cities have amended their city code with an ordinance making it unlawful to park your vehicle and leave it unattended on any private street or any off-street public or private property.
Leaving your keys in your ignition, especially if you do so while leaving the car running, makes your car an easy target for thieves. Depending upon the terms of your auto insurance policy, your insurer may be able to deny claims if you are negligent and leave the keys in your vehicle so that it can be stolen. Take precautions and follow state laws to ensure your vehicle is not vulnerable to thieves.
— Michelle Megna contributed to this story.