Yes, 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 their 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, which is titled Unattended Motor Vehicle. Here it states that an 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; and

(5) if standing on a grade, turning the front wheels to the curb or side of the highway.

The Austin Police Department notes that unattended vehicles found with keys in the ignition can be cited with a fine typically under $200. Officially an offense under this section is punishable by:

  1. a fine not to exceed $200.00;
  2. confinement in a county jail for not more than 30 days; or
  3. both fine and confinement.

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, at least one Texas court has held that this section of 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 in a similar manner.

To close what may be seen as a loophole, many cities have amended their city code with an ordinance making it unlawful to park and leave unattended, upon any private street, or upon any off-street public or private property used for parking and accessible to the public, a motor vehicle with the engine running or that has a key in the ignition.

Leaving your keys in your ignition, especially if you do so while also leaving the car running, can make 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 make sure that your vehicle is not vulnerable to thieves.