The amount is the maximum penalty and would be the most NHTSA has levied against an automaker. The agency said Toyota waited at least four months to alert it of the potential pedal problem. In a statement, Toyota acknowledged the penalty, and said it is taking steps to improve communications with regulators. The company did not comment directly on the possible fine, and has two weeks to decide if it will contest it.

Toyota issued repair procedures for unintended acceleration problems on Sept. 29, 2009, in Europe and Canada. NHTSA said Toyota was aware of similar issues in the United States but waited until January to launch a recall.

NHTSA says manufacturers are required to notify the agency in five business days when they are aware of a safety defect.

“We now have proof that Toyota failed to live up to its legal obligations,” LaHood said in a statement. “Worse yet, they knowingly hid a dangerous defect for months from U.S. officials and did not take action to protect millions of drivers and their families. For those reasons, we are seeking the maximum penalty possible under current laws.”

Toyota's statement said: "While we have not yet received their letter, we understand that NHTSA has taken a position on this recall. We have already taken a number of important steps to improve our communications with regulators and customers on safety-related matters as part of our strengthened overall commitment to quality assurance.

"These include the appointment of a new chief quality officer for North America and a greater role for the region in making safety-related decisions."

The fine would be $16.375 million and is directly for the pedal problem, NHTSA said. The agency said it is still investigating Toyota to determine whether there are additional violations.

NHTSA began its investigation in February to determine whether Toyota's recalls were conducted soon enough. The company has submitted more than 70,000 pages of documents to the government as part of the investigation.