According to NBC affiliate WMAQ, two deaths in Florida have now been linked to problems with keyless ignition systems.
The feature, seen in millions of cars on the road, is believed to have played a factor in the death of an elderly couple in Boca Raton.
Investigators, looking into the couple's death, say the pair died from carbon monoxide poisoning.
Officials believe that a Mercedes with keyless ignition was left running in an attached garage at the couple's home.
In a report following the death, WMAQ reported that keyless ignition systems have been linked to at least five carbon monoxide deaths and numerous injuries across the country.
Those who are critical of the system say that it makes it too easy for drivers to forget to turn their car off, or inadvertently turn it back on remotely.
The National Highway Traffic Safety Administration has said it would take a look at the emerging problem.
So far, the agency says it's been "unable" to decide on a specified period of time after which a car left running should shut off, which is what some safety experts say is the most critical piece of the keyless problem.
The NHTSA is still taking comment on the issue.