The National Highway Traffic Safety Administration announced late Wednesday that it has opened an investigation into "the timeliness of General Motors' recall of faulty ignition switches to determine whether GM properly followed the legal processes and requirements for reporting recalls."
Federal rules require an automaker to notify NHTSA within five business days of determining that it has a safety defect in its vehicles.
GM spokesmen Alan Adler said, "We certainly will cooperate fully" with the probe.
The GM recall -- covering the 2005-2007 Chevrolet Cobalt and 2007 Pontiac G5 on Feb. 13 and expanded on Tuesday to include the 2003-2007 Saturn Ion, 2006-2007 Chevrolet HHR, 2006-2007 Pontiac Solstice and 2007
-- now totals 1.37 million vehicles in the U.S., plus an additional 253,519 in Canada and Mexico.
GM says owners will begin receiving notices in March, and dealers will begin replacing ignition switches in April.
There have been 33 crashes and 13 deaths now linked to the recall. Eight of the deaths were in crashes involving the Cobalt or nearly identical Pontiac G5, five in crashes involving the Ion.
In its announcement, NHTSA urged users of these vehicles to heed GM's recommendation to "use only the ignition key with nothing else on the key ring" when driving and to promptly get the recall repair done as soon as GM begins the repairs.
A schedule for notifying owners and having parts to do the repair -- replacing the ignition switched in the affected cars -- has not yet been announced. NHTSA said it would "monitor consumer outreach as the recall process continues and take additional appropriate action as warranted."