LOS ANGELES — Toyota has recalled more than 1 million of its Corolla and Matrix cars, just days after U.S. auto safety regulators stepped up a probe into the risk that the vehicles could stall because of defective electronic engine control units. The recall also affects 200,000 Pontiac Vibe models built by a joint venture between General Motors Co. and Toyota.

Toyota Motor Sales U.S.A. Inc. said Thursday that the recall of the 2005 to 2008 model year vehicles sold in North America was to address a problem with an electronic component called an engine control module that might have been improperly manufactured. No other Toyota or Lexus vehicles are involved in this recall.

The automaker said there were three unconfirmed accidents alleged to be related to this condition, one of which might have resulted in a minor injury.

Toyota has known about the engine problem since 2005, when it issued dealers a notice — called a technical service bulletin — that explained how to fix it. Owners, however, were not notified that their vehicles had a problem that could cause them to stall suddenly.

“”We have known about the fact that there have been complaints of stalling engines,”” Toyota spokesman John Hanson said. The automaker decided to issue a recall after it conducted more rigorous testing recently and found that the component was failing about 13 percent of the tests, Hanson said.

Federal safety regulators this week had began an engineering analysis of stalling in Corolla and Matrix cars. The National Highway Traffic Safety Administration had received 26 complaints of vehicles stalling when it opened a preliminary evaluation in November. It reported 163 complaints when it opened the engineering analysis.

“”The engine can stall at any speed without warning and not restart,”” NHTSA said on its website.

Before the recall, if a customer complained about the issue, the dealer would be expected to make a repair during the warranty period and charge the expense to the automaker. If the complaint came after the warranty expired, Toyota left it to dealers to decide whether they wanted to fix the problem on their own dime or charge the customer.

Now that Toyota has issued a formal recall, dealers won’t charge for the repair regardless of when the car was bought, and the automaker will reimburse customers who can demonstrate they paid to have the fix made.

This latest recall brings the number of vehicles Toyota has recalled in the last year to about 10 million worldwide, a figure that is approaching the total number of vehicles that will be sold by all manufacturers in America this year. The quality issues have affected the automaker’s sales position and hurt its once-sterling reputation for reliability and dependability. Through the first seven months of this year, Toyota’s U.S. market share dropped to 15.2 percent from 16.3 percent, putting it in third place in the U.S. auto market behind General Motors and Ford Motor Co.

Toyota has been plagued by a rash of quality problems involving faulty gas pedals, floor mats, brakes, electronic stability control systems, steering systems and other defects. Now the engine control units are added to the list.

“”Just when Toyota was likely feeling the long tentacles of the dreaded recall monster begin to release their grip on the company and its vaunted brand equity, along comes news”” of the Corolla problems, said James Bell, an analyst with auto pricing information company Kelley Blue Book.

Whether this recall, on top of so many previous actions, makes any difference to consumers is questionable, said Jessica Caldwell, an analyst at auto information company Edmunds.com.

“”People have pretty much lumped it all into one and tuned it out,”” Caldwell said.

Toyota says there is a crack that may develop either at various points on or in the component in the Corollas. Sometimes it can sever a soldered electronic connection, and in other cases it can cause a failure in the way the circuit board is protected from excess voltage. The crack can cause the check engine light to go on and the driver may experience harsh shifting. The engine may not start, and in some instances the engine can stall while the vehicle is being driven.

Other automakers, wanting to avoid the criticism Toyota attracted previously by being slow to take action, are also issuing more recalls more quickly, and consumers are starting to accept such actions as part of the auto business, Caldwell said.

Toyota plans to replace the module on all of the recalled vehicles at no charge to owners. It will mail notice of the recall to owners starting in mid-September. People will be told to bring their cars to dealers as replacement parts become available. Car owners with questions can go to http://www.toyota.com/recall/ or call Toyota at 800-331-4331.

Owners of the 2005 to 2008 model year Vibes will receive recall letters in September from GM. Because GM closed the Pontiac brand and its dealership network, Vibe owners must take their vehicles to other GM dealerships for the free repair. The Vibe was designed and engineered by Toyota, GM said.