Toyota Motor Corp. resumed full production at all North American plants this week and said it will expand U.S. output of small engines as Japan's largest automaker works to boost sales slowed by a March earthquake.

As of this week, "all plants and suppliers in North America are at full speed, and most are working overtime," Steve St. Angelo, executive vice president for North American engineering and manufacturing, told reporters Tuesday in Torrance, California. "Our parts problems are now behind us."

Toyota will also add production of four-cylinder engines at its plant in Huntsville, Alabama, St. Angelo said. The company will hire 240 more workers at the factory, which already makes six- and eight-cylinder engines for Toyota models built in the region, he said. Four-cylinder output will start late this month, said Mike Goss, a Toyota spokesman.