DETROIT — The US government’s auto safety watchdog is investigating whether General Motors acted quickly enough to recall 1.6 million older-model small cars in a case linked to 13 deaths.
The National Highway Traffic Safety Administration said Wednesday night that it opened the inquiry ‘‘to determine whether GM properly followed the legal processes and requirements for reporting recalls.’’ The agency can fine GM up to $35 million.
On Tuesday, GM doubled the number of cars in the recall for faulty ignition switches. It also issued a rare apology, saying its process to examine the problem was not robust enough a decade ago.
A chronology by GM shows it knew of the problem as early as 2004. ‘‘The chronology shows that the process employed to examine this phenomenon was not as robust as it should have been,’’ said GM’s North America president, Alan Batey.
On Feb. 13, GM announced the recall of over 780,000 Chevrolet Cobalts and Pontiac G5s ( 2005-2007). On Tuesday, it added 842,000 Saturn Ion compacts (2003-2007), and Chevrolet HHR SUVs, Pontiac Solstice, and Saturn Sky sports cars (2006-2007).