TOKYO (AP) — The U.S. government has beefed up its investigation into Toyota's Corolla and Matrix vehicles because of a possible engine defect that might cause them to stall.
The National Highway Traffic Safety Administration said in a statement that it was raising its preliminary evaluation to a more serious scrutiny called an engineering analysis to look into the problems that could cause the engine to stall, not start or to shift gear harshly.
The investigation into the 2005, 2006 and 2007 model year Corolla and Corolla Matrix cars in the U.S. began Aug. 18, NHTSA said.
Toyota spokeswoman Monika Saito in Tokyo confirmed the NHTSA investigation, and said Toyota was cooperating fully but declined to give more details.
Toyota is battling to patch up its reputation after recalling some 10 million vehicles around the world since October last year for a range of defects in floor mats, gas pedals and braking software.
A problem with the Corolla, one of Toyota's top-selling models, would be a further embarrassment for the world's top automaker, which long prided itself on impeccable quality controls.
Toyota is studying two possible causes for problems in the engine control units, both production defects, related to improper coating applied to circuit boards and a crack in the surface of a glass coating, according to NHTSA.
It is unclear whether a recall will be necessary.
Toyota plans to build the Corolla at its northeast Mississippi at Blue Springs beginning in the fall of 2011. Toyota has said the plant will have about 2,000 employees once it hits full operation in 2012.
