DETROIT — The U.S. government’s auto safety agency acknowledged Friday that staffers’ failure to understand technology and lack of skepticism prevented them from rooting out a deadly problem with General Motors ignition switches for more than a decade.

The mea culpa came Friday as the National Highway Traffic Safety Administration outlined actions designed to make itself more aggressive in finding and solving safety problems among the 240 million cars on U.S. roadways. It’s the first time the agency has admitted fault in failing to discover the switch problem and link it to a series of fatal accidents, although regulators still blame the automaker for hiding the defect.

Mark R. Rosekind, administrator of the National Highway Traffic Safety Administration

The GM switches, used in older-model small cars such as the Chevrolet Cobalt and Saturn Ion, can slip out of the run position and abruptly cut off the engine and disable air bags. They’re responsible for at least 109 deaths and more than 200 injuries. The company recalled 2.6 million cars with the switches last year.

NHTSA Administrator Mark Rosekind said the case changed the agency’s culture. Previously, information from automakers largely went unchallenged, but now investigators are questioning data and assumptions about safety issues to make sure they are accurate, Rosekind said.

Problems with the GM switches surfaced in the early 2000s. But Rosekind said agency staffers didn’t fully understand air bag technology, and therefore didn’t link the ignition switches to crashes in which the air bags should have inflated but did not.

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