Transparency has been a key point for Barra since the crisis began with word of the first ignition switch recall in February. The automaker has since expanded that service action to cover 2.6 million vehicles.
"They had to take corrective action" to prove that her promise to come clean wasn't just meaningless words, said Don Tanner, a reputation specialist with Detroit's Tanner Friedman.
"I think [Barra] took an important step today," he said.
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The first woman to serve as CEO of a major automaker, Barra initially won strong praise. But she took a beating during April hearings on Capitol Hill that looked into the ignition switch problem.
Although Thursday's report concluded she didn't know about the problem during her prior job as GM's global product development chief, it's ultimately her responsibility that GM makes real changes, experts said.
"We need more than an accounting of past mistakes; we need to ensure accountability and that permanent measures are put in place to prevent future deaths," Sen. Ed Markey of Massachusetts said in a statement.
Thursday's report, prepared by former federal prosecutor Anton Valukas, found that GM could have done a far better job of dealing with a defective ignition switch that has been linked to at least 13 deaths. The probe has already led to the dismissal of 15 GM employees—most of them senior managers or executives—while five others have been disciplined.
—By CNBC Contributor Paul A. Eisenstein. Follow him on Twitter@DetroitBureau or at thedetroitbureau.com.