GM CEO Mary Barra will take "significant actions" that include holding specific employees accountable for the ignition switch defect that has plunged the automaker into a crisis.
"Mary will not be holding back and will be extremely candid" sources familiar with the investigation and its conclusions told CNBC.
Thursday morning Barra is expected to outline a number of steps the company has taken or will take as a result of an internal investigation conducted by former U.S. Attorney Anton Valukas.
Sources would not comment on whether those steps include firing employees linked to the defective ignition switch and GM's failure to notify the public and federal investigators about the flawed part.
However, those familiar with internal probe say Barra will "not be holding back or glossing over of the facts about what went wrong."
Read MoreGM apologizes for recall notices
General Motors said 13 deaths and 47 accidents have been linked to 2.6 million models recalled because of defective ignition switches.
Changing the GM structure
A key part of the investigation into why GM failed to act sooner is whether or not the way in which the automaker is structured contributed to its slow action on safety issues.