WASHINGTON — Lawmakers investigating why General Motors took more than decade to order a recall to fix a deadly ignition switch defect Wednesday pressed CEO Mary Barra about her efforts to alter the company’s often unresponsive internal culture.

Making her second appearance before a House subcommittee probing GM in connection with the defect tied to 54 accidents and 13 deaths, Barra, a GM lifer, faced skeptical questions about whether she could change a company notorious for its stilted and uncommunicative bureaucracy.

Barra’s appearance came less than two weeks after GM released the results of an investigation into why it took GM more than a decade to recall a defective switch that caused cars to inadvertently stall, stiffening brakes and steering and disabling air bags.

“I know some of you are wondering about my commitment to solve the deep underlying cultural problems uncovered in this report,” Barra told the committee. “The answer is I will not rest until these problems are solved.”

The recalls have cost GM $2 billion, and the automaker also is facing dozens of lawsuits in connection with the delayed recall. On Wednesday, the automaker was hit with a potential class action filed in federal court in California alleging that owners of GM cars have seen the values of their cars decline because of the recall saga.

GM’s probe, led by former U.S. attorney Anton Valukas found a pattern of “incompetence and neglect” inside GM but no conspiracy to hide the problem, which affected 2.6 million Chevrolet Cobalts and other small cars.

Barra was also grilled about a GM recall on Monday of more than 3 million cars to fix an ignition switch defect similar to the one that affected its small cars.