Honda failed to notify U.S. safety regulators of approximately 1,729 claims of injuries and deaths related to accidents in its vehicles since 2003.
The automaker said its count of underreported claims came from a third-party audit, according to a company statement. Honda cited "various errors related to data entry" and said it used "overly narrow interpretation" of its legal reporting requirements.
Honda said it is taking the necessary steps to "remedy these shortcomings."
"I haven't got a detailed report yet, but it seems there were a lot of administrative mistakes on the ground," Honda CEO Takanobu Ito told said during a corporate event in southern Japan on Tuesday, according to Reuters.
Honda said it did not report 1,729 death and injury claims from July 1, 2003, through June 30, 2014. During that period, the company reported 1,144 claims, it said in statements, according to the Associated Press.
The unreported claims included one death and seven injuries to faulty Takata air bag inflators.
The response was due to a Nov. 3 order sent to Honda by the National Highway Traffic Safety Administration. The NHTSA was looking for a reason why the Japanese automaker didn't fulfill it legal obligations to report deaths and injuries, especially those involving air bags.
Honda and supplier Takata have been the focal point of investigations of defects in Takata air bags. Since 2008, Honda has recalled more than 7.5 million U.S. vehicles because defects can cause inflators in some air bags to rupture, spraying metal shards into vehicle occupants.
Ito also responded to questions about an early, pre-recall Takata air bag accident, in 2004.
"We don't have knowledge of inflators but it was difficult to foresee that it would expand" to similar recalls or incidents, Ito said.
A second order was sent to Honda by NHTSA on Nov. 5, looking for details and documents related to inflators and air bags. The automaker responded on Monday to the first order.
A summary of that response was read by Rick Schostek, executive vice president of Honda North America, during a conference call. He declined to take questions however.
Honda acknowledged that one of its employees recognized the data entry errors back in 2011. The company was made aware of under-reporting by NHTSA in January of 2012.
"Honda began looking into the issue at that time, but did not take conclusive action," Executive Vice President Rick Schostek said during a teleconference with reporters, according to the AP.
The automaker is taking "corrective action" to make sure these issues don't happen again.
See Now: OnePlus 6: How Different Will It Be From OnePlus 5?