People walk by a Ford Escape SUV displayed during the media day for the Shanghai auto show in Shanghai, China, April 16, 2019.

The company also said it cannot predict the outcome of the investigation and "cannot provide assurance that it will not have a material adverse effect on us."

Ford made the disclosure in an SEC filing Friday. It said the company is cooperating fully with all government investigations, and has notified several state and federal agencies.

The matter stems from issues related to road load estimations, including analytical modeling and physical track testing. Road load is a vehicle-specific resistance level that helps determine fuel economy ratings and emissions certifications. It does not involve the use of defeat devices to cheat on emissions tests.

"Our focus is on completing our investigation and a thorough technical review of this matter and cooperating with government and regulatory agencies," Kim Pittel, Ford's vice president of sustainability, environment and safety engineering, said in a statement."

Ford voluntarily disclosed the issue to the Environmental Protection Agency on Feb. 18 and the California Air Resources Board on Feb 21. Ford has hired outside experts to investigate its vehicle fuel economy and testing procedures after employees raised concerns. Since last fall, Ford has been looking into concerns that incorrect mathematical calculations could have impacted mileage and emissions data submitted to regulators.

Since 2015, U.S. and California regulators have cracked down on automakers who cheat on emissions testing after Volkswagen's use of defeat devices became public knowledge.

The automaker's stock is up 6.8% in premarket trading after it reporting quarterly earnings that topped expectations.

WATCH: Ford CFO Bob Shanks breaks down first-quarter earnings