In late November, the National Highway Traffic Safety Administration opened an investigation into the Toyota Corolla and Matrix in response to reports of random and sudden engine stalling. Now, Toyota has contacted NHTSA to inform them it may have found a culprit in the engine computer.
"Toyota does not believe that the alleged defect creates an unreasonable risk to motor vehicle safety," Chris Santucci, Toyota's regulatory affairs manager, wrote in a letter to NHTSA.
In the letter, Toyota identified the Engine Control Unit, the computer that runs the engine, as the culprit in the sudden and random engine stalls. Toyota believes that a crack in a soldered joint inside the computer could be to blame, or possibly an electrical short. Either problem could cause the engine to shut down or fail to start. According to the letter, Toyota believes that an engine stall is the safest outcome of such a failure.
NHTSA began investigating the problem in late November after receiving 26 complaints of sudden engine stalls in the Corolla and Matrix models, which are essentially the same under the skin. The problem only affects the four-cylinder engine and appears to occur at random. Nearly half of the reported cases occurred while driving, but no injuries or deaths have been reported. A replacement ECU appears to be all that is necessary to alleviate the problem.
While the exact cause of the stalling hasn't been pinpointed, Toyota said in the letter that it would like to meet with NHTSA to delve deeper into the issue. No recall has been announced yet, but Toyota says in the letter that the problem could potentially affect 1.19 million Matrix and Corolla models from the 2005, 2006 and 2007 model years. Some Corolla and Matrix models are already under recall for faulty floor mats and sticking accelerator pedals. Toyota has not said if this ECU problem is in any way related to the sudden unintended acceleration issue, but it doesn't appear to be, since it has the opposite effect.