Washington state troopers filed a lawsuit seeking class-action status last week alleging Ford Police Interceptor Utilities based on the Ford Explorer design exposed officers to noxious gases, causing sickness and physiological injury.

The suit, filed Aug. 7 in Superior Court of Washington’s Clark County, blames a defective exhaust, ventilation and heating or air conditioning system in 2014-17 Explorers allowing exhaust odor and gases including carbon monoxide “to enter the passenger compartment of vehicles while in use.”

The six plaintiffs claimed they suffered headaches, nausea, foggy thinking or flu-like symptoms from driving the vehicles and one “suffered permanent neurological damage which has prevented him from continuing his job as a Washington state patrol trooper.”

In a statement, Ford said some Police Interceptor Utility vehicles were found to have “unsealed holes from the installation of police equipment by third parties after the vehicle was purchased.”

The lawsuit was reported by the Detroit Free Press.

Consumer complaints to NHTSA of exhaust odors prompted an investigation in July 2017, which is still ongoing, into Ford Explorers from the 2011-2017 model years.

NHTSA told Automotive News in an emailed statement that it has tested police and civilian Explorers, evaluated consumer complaints and monitored the effectiveness of Ford’s customer service repair campaigns.

“NHTSA will publicly release the agency’s conclusions when the safety defect investigation is completed,” the safety agency said.

One 2017 NHTSA document stated: “To date, no substantive data or actual evidence has been obtained supporting a claim that any of the alleged injury or crash allegations were the result of carbon monoxide poisoning. … The Police Interceptor version of the Ford Explorer is experiencing exhaust manifold cracks, which appear to present a low level of detectability, and may explain the exhaust odor.”

In its statement Ford said: “Explorers are safe. Owner complaints to Ford and NHTSA have decreased dramatically since we announced our complimentary service for exhaust odor in the fall of 2017, as it effectively resolves the matter. We continually monitor customer concerns, including those to NHTSA. If an owner has concerns, they should contact their dealer for inspection.”

Ford reported working with law enforcement agencies to address carbon monoxide concerns in some Police Interceptor Utilities in August 2017.

Inspections of police vehicles across the U.S. found “holes and unsealed spaces,” in the backs of vehicles which had “customized emergency lighting, radios and other equipment” installed after leaving the factory, Ford said in 2017.

“If the holes are not properly sealed, it creates openings where exhaust could enter the cabin,” Ford said at the time.

As a part of the action, Ford provided an air conditioning calibration “that brings in more fresh air during heavy acceleration typical of police driving,” sealed off rear openings, and checked the engine for codes indicating a damaged exhaust manifold, the release said. The automaker covered the cost of some repairs in vehicles with the concern.

In 2017 and again in 2018 the Center for Auto Safety called for a recall of 1.3 million 2011-17 Ford Explorer vehicles following an increase in complaints of carbon monoxide leaks.

Jason Levine, executive director of the center, told Automotive News that Ford’s response to complaints was “insulting to consumers.”

Ford has “continued to insist that it’s not an issue and that the problems happening with the Interceptors were solely about after-market adjustments,” Levine said. “The Explorer and Interceptor are essentially the same vehicle, and no one’s putting after-market police gear on their Explorer and yet they’re having the exact same problem.”