DETROIT — General Motors Co. is adding 970,700 vehicles to its ignition switch recall because 90,000 of those vehicles in the 2008 through 2011 model years may have had good switches replaced with bad ones.

The recall – which previously covered 1.6 million small cars from the 2003 through 2007 model years – now includes all versions of the Chevrolet HHR, Chevrolet Cobalt, Saturn Sky, Saturn Ion, Pontiac Solstice and Pontiac G5.

All of those vehicles were made through 2010, except the HHR which was also made in 2011. The expanded recall affects 824,000 vehicles in the U.S., 132,000 in Canada, 5,700 in Mexico and 9,000 in the rest of the world.

“We know these vehicles were built with good switches but there’s a possibility, if they were repaired, that they might have gotten a bad switch,” GM spokesman Jim Cain said. “To leave no stone unturned and not take any chances, we’re going to recall all of them and not take any chances.”

Although the 2008 through 2011 model-year vehicles were made with good switches, some of them were replaced with faulty parts distributed to the aftermarket. GM says about 90,000 defective switches were installed in vehicles.

The automaker said it is not aware of any crashes or deaths involving the 90,000 defective switches installed in 2008 through 2011 model-year vehicles.

The 1.6 million vehicles recalled in February have been linked to at least 31 crashes and 12 deaths. The problem is that the ignition switch could move into the accessory position while the vehicle is still moving, causing the driver to lose power steering, brakes and air bags.

The National Highway Traffic Safety Administration, which is facing its own investigation over its handling of the situation, said the recall comes “after NHTSA’s continued engagement” in the crisis.

“Consumers impacted by GM’s safety recall should have their vehicles serviced promptly once they receive notification,” the agency said. “The agency will monitor consumer outreach as the recall process continues and take additional appropriate action as warranted.”

Repair shops could have used defective ignition switches originally supplied by Delphi. Engineers made the mistake of labeling new parts with the same number as the original part, so there’s no way to know if a car received a bad switch.

In 2007, Delphi made the internal spring tighter so a weighed-down key could not cause the ignition to switch from power to accessory mode. But neither GM nor Delphi changed the part number.

GM engineers discovered a problem about a decade ago, but the company failed to initiate a recall until this year, prompting a flood of lawsuits and government investigations.

GM CEO Mary Barra, who has apologized for the problem, will testify before congressional committees Tuesday and Wednesday. “We are taking no chances with safety,” Barra said in a statement.