The National Highway Traffic Safety Administration (NHTSA) is looking into 724,000 Ford Escape, Fusion and Mercury models after receiving several reports of sudden loss of engine power.

NHTSA has opened a safety investigation into the 2009-2011 Escape and Fusion, and Mariner and Milan.

The agency said it had 123 reports involving complaints of reduced power or vehicle stall in Escape vehicles under investigation. To address complaints, Ford modified the model design in 2009 but did not recall the vehicles, reported the Detroit News. There have been 27,500 warranty claims for the issue and reports of three crashes and one injury, according to NHTSA. Ford has received over 1,400 complaints.

Ford spokeswoman Kelli Felker said: "We are cooperating fully with NHTSA on this investigation, as we do on all investigations."

There may be contaminated circuit boards with plating variations in vehicles manufactured between June and October 2009 which could result in failures. Vehicles made after 15 October 2009 feature electronic throttle bodies manufactured with a new process which solved the problem. A technical service bulletin by the company told dealers to replace the throttle body on several Ford and Lincoln vehicles.

NHTSA said certain Ford vehicles being examined were identified as failed electronic throttle bodies with diagnostic trouble codes P2111 Throttle Body Stuck Open, and P2112 Throttle Body Stuck Closed. A driver may see varying levels of reduced engine performance, based on the condition of throttle control system malfunction.

NHTSA also received 59 complaints for model year 2010-11 Ford Fusions, over engine stalling while driving. Fourteen complaints said the throttle body was replaced or error codes were related to limp-home modes.

NHTSA opened the formal probe after receiving a petition in August from the North Carolina Consumers Council which called for a broad investigation into electronic throttle body malfunctions that caused engine stall or surge in 2005-12 Ford Escapes.