Ford is recalling almost 24,000 Focus Electric and C-Max cars because they don’t make a chime when the driver’s door is open and the key is still in the car.

This is one of those odd federal regulations meant to keep drivers from leaving new generation electronic keys — called fobs and smart keys — behind when they exit the car.

Federal regulators worry that cars will get stolen if drivers leave their electronic keys behind

This recall includes 2012-13 Focus Electric sedans and 2013 C-Max hybrids, the automaker said. The cars were sold in the U.S. and Canada.

Smart keys were once available only in luxury brands such as BMW, Mercedes-Benz and Lexus but now are offered by most automakers either standard or as an option.

As cars transition from metal keys that have to be physically turned to switch the motor off to push-button electronic ignitions, providing a warning has become more important.

This issue presents a theft risk, but depending on the manufacturer and the key system, a driver could also be locked out.

AAA said it rescued 4 million drivers who locked themselves out of their cars last year.

AAA says it expects smart keys to be transitional technology, soon to be replaced by people’s phones.

Will that lead to some new regulation against leaving your phone in the car?