The carmaker reported $3.1 billion in profit from July through September, which included two weeks of walkouts by the United Automobile Workers.
The Department of Justice has sought documents related to vehicle range and “personal benefits,” Tesla said.
The carmaker made less money in the third quarter as it cut car prices to attract buyers amid stronger competition.
Analysts expected a decline in sales for the quarter. Still, the dip may raise concerns about flagging demand.
The automaker made more money on trucks and sport utility vehicles but reported bigger losses on electric vehicles.
The German automaker lowered its outlook for deliveries and announced changes to its China strategy as it struggles to regain ground lost to other automakers.
The company is earning big profits on gasoline cars and trucks but is struggling to catch up to Tesla in the fastest-growing segment of the auto market.
Elon Musk’s electric car company is facing intensifying competition from newer Chinese automakers and established Western car companies.
The automaker saw a big jump in deliveries of pickup trucks as demand from consumers and businesses remained strong.
The biggest U.S. automaker sold more trucks and sport-utility vehicles as supply chain problems eased and demand remained strong.