WASHINGTON — The National Highway Traffic Safety Administration opened an investigation into the 2011-'15 Ford Explorer SUV after consumer complaints about exhaust odor.
Occupants reported smelling exhaust odors in the passenger compartment, NHTSA said in a posting on its website on Tuesday.
There are 154 complaints linked to the probe and one alleged low-speed crash incident, but no injuries.
"Complainants expressed concerns about exposure to carbon monoxide," NHTSA said in its problem description.
NHTSA did not reveal how many Explorers are involved in the investigation, saying only that the number is "confidential" at this point.
"Complaints indicate that operating the vehicle with full-throttle applications (climbing steep grades or merging onto freeway ramps) and use of the air-conditioning system in recirculation mode both contribute to exhaust gas being detected in the vehicle," NHTSA said.
Ford issued two related Technical Service Bulletins in December 2012 and July 2014 that addressed the problem. The most recent repair added additional software to the recirculation-mode operation of the air-conditioning system during full-throttle application.
But "some owners reported little or no improvement after the TSB remedy," NHTSA said.
Federal safety regulators opened a "preliminary evaluation" into the affected Explorers. Such an action sometimes precedes a vehicle recall.
"This investigation is opened to evaluate any potential driver-related safety concerns caused by this issue," NHTSA said.
Ford will cooperate with NHTSA on this investigation, Ford spokeswoman Elizabeth Weigandt told Edmunds.
A 2012 Ford Explorer was previously part of Edmunds' fleet of long-term test vehicles, but we did not experience this particular issue during our yearlong test.
Edmunds says: The 2011-'15 Explorer has not been recalled for exhaust odor at this point. But if you own one of these vehicles and have an immediate concern, it's best to contact your Ford dealer now.