Updated

The Justice Department could soon announce a settlement with Toyota that would conclude a four-year investigation by the department into the carmaker's disclosure of safety issues with its vehicles.

The Wall Street Journal reported late Tuesday that the announcement of a settlement could come as early as Wednesday and could include a fine of up to $1 billion, which would be among the largest fines ever imposed on an auto manufacturer. However, people said to be familiar with the matter told the Journal that the settlement was not final and could still fall apart.

The investigation has focused on whether or not Toyota properly disclosed issues related to unexpected acceleration in its cars. The National Highway Traffic Safety Administration said in 2010 that five people had died as a result of accidents involving unexpected acceleration.

The Journal, citing a government official who'd been briefed on the legislation, reported that the investigation found that Toyota had made misleading statements to the government and the public about the issue that contradicted the company's internal audits.

However, the NTHSA never found flaws in the electronic throttle-control or control software of the cars in question and determined operator error or floor mats trapping accelerator pedals were involved in most accidents. That squares with claims made by the company in response to  lawsuits claiming that their vehicles are defective.

The auto maker has been fined four times for a total of $66.2 million by NHTSA for failing to report safety defects to the government. Three of those fines were related to issues concerning unwanted acceleration.

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