The recall now includes all model years of the Chevrolet Cobalt, Chevrolet HHR, Saturn Ion, Saturn Sky, Pontiac G5 and Pontiac Solstice made from 2003-2011.
At least 12 deaths have been linked to the defect in the ignition, which when jostled or bumped can switch itself into "accessory" mode, even at highway speeds, shutting down the engine and disabling power steering, power brakes and airbags.
The expanded recall follows a Reuters report on Wednesday that it was still possible to purchase GM-brand ignition switches manufactured by Delphi Automotive carrying the same part number as the product at the center of the February recall.
GM redesigned the faulty part for model years after 2007, but it did not change the part number, and it fears that some newer-model cars could have been repaired with defective older-model switches.
Switches still available in parts stores may not be defective, but it is nearly impossible to tell new ones from older-design ones unless they are taken apart or the manufacturing history is checked, Reuters reported.
Even before the expansion, the recall had sparked investigations by Congress, federal regulators, the Department of Justice and GM itself. All are asking why it took GM so long to address an issue first noted by the company in 2001.
GM Chief Executive Mary Barra said on Friday that "we are taking no chances with safety" in replacing the ignition switches on all 2.6 million cars. Barra is due to testify next week before Congress, where she is likely to be grilled on why it took GM more than 10 years to implement the recall.
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971,000 GLOBALLY
The expanded recall adds 971,000 cars globally, including 824,000 in the United States, GM said.
GM also is recalling all the replacement ignition switches that have been sent to US aftermarket distributors, the spare parts market. About 95,000 faulty switches were sold to dealers and parts wholesalers, of which about 5,000 remain on shelves.
GM said Friday that no deaths or injuries have been linked to faulty ignition switches in the newer models that have been added to the recall. Older versions of those cars, dating from 2003-2007, were recalled in two tranches in February.
GM had said on Thursday that the replacement ignition switch it has ordered from Delphi to use in the earlier recall will bear a new part number that "eliminates any potential confusion about which part to use in the repair," according to a company spokesman.
GM said owners will be notified by mail the week of April 21 and can have ignition switches replaced for free at dealers "as parts become available" -- a process that is likely to take months because of the sheer number of vehicles involved.
GM also launched a website, www.gmignitionupdate.com, to provide consumers with information on the recall.
GM replaced the Cobalt in 2010 with a newer compact, the Cruze. On Friday, the automaker told US dealers to stop selling certain 2013 and 2014 Cruze sedans equipped with 1.4-liter engines without saying why.