"We enlisted the best and brightest engineers to study Toyota's electronics systems, and the verdict is in. There is no electronic-based cause for unintended high-speed acceleration in Toyotas," said U.S. Transportation Secretary Ray LaHood in a release Tuesday.
The federal watchdog National Highway Traffic Safety Administration commissioned the study by the National Aeronautics and Space Administration at the request of Congress last spring, after Toyota initiated recalls of nearly 8 million vehicles in the United States blaming floor mats and "sticking" accelerator pedals.
Toyota paid nearly $33 million in civil penalties for not notifying NHTSA of the potential defects in a timely manner.
NASA engineers with expertise in computer controlled electronic systems, electromagnetic interference and software evaluated the circuitry in Toyota vehicles and analyzed more than 280,000 lines of software code for potential problems, NHTSA said.
"NASA found no evidence that a malfunction in electronics caused large unintended accelerations," said Michael Kirsch, principal engineer at the NASA Engineering and Safety Center.
NHTSA said, despite the report's findings of no electronic flaws, it was considering proposing rules this year to require brake override systems, to standardize operation of keyless ignition systems and to require installation of event data recorders in all passenger vehicles.