The National Highway Traffic Safety Administration has ended a six-year safety probe into the 2011-2017 Ford Explorer over concerns the vehicles leaked carbon monoxide into the cabin.
The investigation into nearly 1.5 million potentially affected vehicles determined that a recall is not warranted.
Three deaths and 657 injuries had been reported that were allegedly linked to exhaust fumes entering the cabin.
Many of the complaints involved Explorer-based Police vehicles.
ST. LOUIS HYUNDAI/KIA DEALER INVENTS SECURITY DEVICE FOR CARS BEING STOLEN THROUGH TIKTOK TREND
The Ford Explorer was all-new for the 2011 model year. (Ford)
Ford had issued a field service campaign in 2017 to seal the vehicles and NHTSA examples that had been through the program by trying to pump fumes into them using various measures.
It did not measure higher than the EPA's allowable levels of carbon monoxide, but conceded that some fumes had leaked into the cabins.
The Police Interceptor Utility vehicle is based on the Explorer. (Ford)
"NHTSA recognizes that hypersensitivities to CO and other exhaust gas constituents exist within the overall population," it wrote.
Even vehicles that hadn't been sealed passed the testing, and it identified the primary causes for the complaints were due to the body integrity being compromised by the installation of police equipment and rear crash damage.
CLICK HERE TO SIGN UP FOR THE FOX NEWS AUTOS NEWSLETTER
Ford said in a statement that it was pleased that the investigation found no unreasonable risk to vehicle safety.
The Explorer is among the best-selling SUVs of all-time. (Scott Olson/Getty Images)
"Ford's previous investigation and extensive testing determined the same results, which we have always maintained," the company said.
Ford's sealing repair included checks of gaskets and drain valves and reprogramming the heating and ventilation system to let in more fresh air.
CLICK HERE TO GET THE FOX NEWS APP
The Center for Auto Safety's Executive Director Michael Brooks said that NHTSA should seek a recall of all damaged Explorers to ensure they've been through the sealing process.
The Associated Press contributed to this report