WASHINGTON (AP) -- Complaints of engine stalling on Toyota Corolla sedans and Matrix hatchbacks have caught the attention of U.S. safety regulators.
They're stepping up their investigation but government officials stopped short of announcing a recall.
The National Highway Traffic Safety Administration is looking at two possible causes: Improper coating on circuit boards and a crack in the surface of a glass coating. Both could have happened during production of the cars.
The new probe, called an engineering analysis, covers 1.8 million Corolla and Matrix cars from model years 2005 to 2007.
NHTSA said it has received 163 complaints of stalling engines in the cars as of last week.
A problem with the Corolla, one of Toyota's top-selling models, would further embarrass the Japanese automaker, which has long prided itself on its quality controls.