NEW YORK (CNNMoney.com) -- Government regulators said Tuesday they have demanded documents from Toyota to determine if the automaker conducted its recent recalls in a timely manner.
The National Highway Traffic Safety Administration said it has ordered Toyota to provide documents showing when and how it learned of the defects affecting approximately 6 million vehicles in the United States.
Federal regulations require all automakers to notify NHTSA within five days of determining that a safety defect exists and promptly conduct a recall, the agency said.
"Safety recalls are very serious matters and automakers are required to quickly report defects," said U.S. Transportation Secretary Ray LaHood.
The move comes amid a spike in customer complaints lodged against Toyota in the NHTSA database, including some that allege fatal crashes were caused by sudden acceleration in Toyota cars since Jan. 27.
The probe will examine how Toyota learned of the defects. For example, regulators want to know if Toyota discovered the problems through consumer complaints or factory testing.
The investigation will also focus on whether the company found the problems before the vehicles in question were produced or after they had already been built.
In addition, regulators will check whether Toyota has covered all affected models in its recent recalls to make sure the automaker didn't miss any problems.
NHTSA said it has demanded documents from Toyota on customer complaints, production data, dates of meetings and other pertinent details.
Toyota will have 30 days to provide the documents pertaining to the timeliness of the recalls and 60 days to submit information related to the adequacy of its ongoing recall efforts, according to a Department of Transportation official.
Cindy Knight, a Toyota spokeswoman, said the company is reviewing NHTSA's request and will provide all the information they have requested.
"Toyota takes its responsibility to advance vehicle safety seriously and to alert government officials of any safety issue in a timely manner," she said.
Toyota has recalled more than 8.1 million vehicles worldwide for problems related to sudden acceleration and unresponsive brake pedals, among other things. The company has apologized for the safety lapses and pledged to repair the recalled vehicles quickly.
The recalls under investigation include two related to the entrapment of gas pedals by floor mats. Those recalls were announced last fall and expanded early this year. The third, announced in January, involved sticking gas pedals.
If the investigation determines that Toyota violated its statutory obligations, NHTSA said the manufacturer could be liable for a fine of up to $16.4 million.
That's the maximum penalty under a 2000 law that established stiffer civil, and even criminal, penalties for automakers that fail to promptly report safety defects to federal regulators in a timely way.
The Transportation Recall Enhancement, Accountability and Documentation Act, or TRED, was passed in response to dozens of deadly Ford Explorer rollover crashes caused by faulty Firestone tires. No fines were ever levied in that case.
The biggest fine that's ever been levied was just $1 million taken from General Motors in 2004 for failing to deal promptly with a windshield wiper issue, an amount that was negotiated down from the $3 million NHTSA originally asked for.
New York City's Bryant Park has always had the nicest public restroom around. But it just got a $300,000 upgrade that made it even more opulent. More
President Trump's tax plan outline suggests there will be a lot of tax cuts for the wealthy. But two would be especially sweet for Trump and his children. More
The robot era is here, and man-on-machine violence is already beginning. More
In 1998, Ntsiki Biyela won a scholarship to study wine making. Now she's about to launch her own brand. More
Becoming a millionaire is part of the American dream, but is it out of reach for the average person? More