General Motors is adding four more late-model vehicles to its recall over ignition switches that can unexpectedly shut off the engine and cause crashes.

The recall affects 588,000 vehicles made between 2003 and 2007 and sold in North America. The models are:

  • 2003-07 Saturn Ion.
  • 2006-07 Chevrolet HHR.
  • 2007 Pontiac Solstice.
  • 2006-07 Saturn Sky.

On Feb. 13, GM recalled 780,000 Chevrolet Cobalts and Pontiac G5s from the 2005 through 2007 model years. The total cars recalled in Canada and the U.S. is 1.37 million.

In Canada, a total of 235,855 vehicles will be recalled.

The ignition defect allows it to move unexpectedly from "run" to "accessory" if jarred or pulled by a heavy key chain. That shuts off the engine and disables the front air bags.

The U.S. National Highway Safety Administration has linked the defects to 31 crashes and 13 front-seat deaths.

According to a chronology of events that GM filed Monday with the National Highway Traffic Safety Administration, the company knew of the problem as early as 2004, and was told of at least one fatal crash in March of 2007. GM issued service bulletins in 2005 and 2006 telling dealers how to fix the problem with a key insert, and advising them to tell customers not to dangle too many items from their key chains. But the company's records showed that only 474 vehicle owners got the key inserts.

GM thought the service bulletin was sufficient because the car's steering and brakes were operable even after the engines lost power, according to the chronology.

By the end of 2007, GM knew of 10 cases in which Cobalts were in front-end crashes where the air bags didn't inflate, the chronology said.

In 2005, GM initially approved an engineer's plan to redesign the ignition switch, but the change was "later cancelled," according to the chronology.

"They knew by 2007 they had 10 incidents where the air bag didn't deploy in this type of crash," said Clarence Ditlow, executive director of the consumer advocacy group Center for Auto Safety. "This is a case where both GM and NHTSA should be held accountable for doing a recall no later than the spring of 2007."

GM North American President Alan Batey said in a statement that the process to examine the problem "was not as robust" as it should have been and said the GM of today would behave differently.

We will take an unflinching look at what happened and apply lessons learned here to improve going forward," he said.