The bulk of the 2000 to 2014 model-year cars -- 3.2 million -- are in the United States, the largest US automaker said yesterday.
GM said that the ignition switch may move out of the "run" position if the key is carrying extra weight and is jarred, such as when the car hits a pothole or crosses railroad tracks.
Switching out of the "run" position affects power steering, power braking and could cause air bags not to deploy in a crash.
GM said it knows of eight crashes and six injuries related to this recall.
The company said the recall stems from its review of ignition issues following the recall in February of 2.6 million Chevrolet Cobalts and other small cars for ignition switch problems.
The cars covered in the newest recall are Buick Lacrosses, Chevrolet Impalas, Cadillac Devilles, Cadillac DTS, Buick Lucernes, Buick Regals, and Chevy Monte Carlos, from various model years between 2000 and 2014.
GM said addressing the problem would involve replacing existing ignition keys with new ones designed differently, or retooling existing keys.
"Until the rework or replacement is completed, owners of the recalled cars are urged to remove additional weight from their key chains and drive with only the ignition key," GM said.
GM also announced US recalls for 165,770 vehicles for a variety of problems, including with automatic transmissions and power steering.
It said it would take a charge of about USD 700 million for recall repairs in the second quarter, including the USD 400 million provision it previously announced.
The automaker is under congressional and, reportedly, Justice Department investigation over why it failed to act on the Cobalt ignition switch problem until this February despite knowing about it for more than 11 years.
That problem has been tied to dozens of accidents and at least 13 deaths, according to GM. Outside analysts have said the death toll could be much higher.
The company is facing multiple lawsuits for that problem, which analysts say could ultimately cost the company billions of dollars in damages.