GM said the key could move out of the "run" position if there was a "jarring" event (such as hitting a pothole) and the keychain was carrying extra weight. That can shut off the engines and disable power steering.
GM says it is aware of eight crashes and six injuries due to this ignition issue.
The recall is part of a GM review of ignition switches after the company recalled 2.6 million older small cars earlier this year for a similar problem. GM also is recalling 166,000 other cars for a series of problems.
The company raised its expected second-quarter charge for recall expenses to $700 million.
The recall includes these cars and model years:
- Buick Lacrosse, 2005-2009
- Chevrolet Impala, 2006-2014
- Cadillac Deville, 2000-2005
- Cadillac DTS, 2004-2011
- Buick Lucerne, 2006-2011
- Buick Regal LS & GS, 2004-2005
- Chevy Monte Carlo, 2006-2008
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