Two years ago, a Lancaster County couple were found dead in their home.

Darryl Morton, 50, and Aida Judy Cora, 54, died at Morton's Manheim Township home due to carbon monoxide poisoning, officials determined six months after their deaths. Their Lincoln, with a keyless ignition system, had been left running in their garage, with the fob that activated the starter still in the car.

Vehicles with keyless ignition are becoming more common, as are concerns about the safety hazards they can cause. The vehicles have sensors that detect fobs carried by a driver, and can be activated simply by pushing a dashboard button.

Because there is no need to take the fob out of a pocket, and there are no keys to put in the ignition, there have been cases of people forgetting to turn off their vehicle when exiting. If a person does so after parking in a garage attached to a house, as Morton and Cora did, the results can be tragic.

On Nov. 20, U.S. Sen. Robert P. Casey (D., Pa.), prompted in part by the deaths in Lancaster County, sent the National Highway Traffic Safety Administration a letter urging it to move quickly to adopt a long-awaited rule that would alert drivers who walk away from a car that's still running.

"Without an alarm or automatic shutoff feature for the ignition system, drivers, families, neighbors, and emergency responders could be at risk for carbon monoxide poisoning," Casey wrote to the federal agency.

At least 13 deaths have been caused by carbon monoxide poisoning from cars with keyless ignitions unintentionally left running, according to a lawsuit filed in August in federal court in Los Angeles against 10 automakers, including Ford, Honda, and Toyota. The suit says 276 models - millions of vehicles - were made with a keyless ignition system. The plaintiffs are seeking to force the auto industry to make keyless systems safer.

"Part of what's so concerning about it is, you can wipe out an entire family if the car's left running in an adjoining structure," said Noah H. Kushlefsky, a New York lawyer who has litigated other cases related to complaints about keyless ignitions.

For years, the NHTSA received complaints from drivers concerned about keyless ignition systems. In December 2011, it proposed a rule that would require automakers, among other things, to include an alarm that would sound if a driver left a vehicle with such a system without turning off the engine. The rule is expected to be approved in February, the agency said in a statement this week.

The auto industry generally follows recommendations from the Society of Automotive Engineers, said Wade Newton of the Alliance of Automobile Manufacturers, a business association of 12 carmakers. He declined to address specific concerns about keyless ignition systems due to the ongoing litigation.

The NHTSA considered, but did not recommend, an automatic shutoff that would kill the engine of a vehicle with a keyless ignition after it had been idle for a certain period. This, more than an alarm, is what some auto safety advocates think is really needed.

"A lot of time everyone just sort of seems to assume everyone has really good hearing," said Rosemary Shahan, president of Consumers for Auto Reliability and Safety, in Sacramento, Calif. "I think it's not a good idea to depend solely on an audible alarm."