US safety officials from the National Highway Traffic Safety Administration have opened an investigation into possible exposure to carbon monoxide in recent models of the Ford Explorer SUV, the regulator's website showed, according to Reuters.

The investigation into model year 2011 to 2015 Explorer SUVs was opened last Friday by NHTSA which said it has identified 154 complaints of "occupants smelling exhaust odours in the occupant compartment," and that some of the vehicle owners "expressed concerns about exposure to carbon monoxide."

"We will cooperate with NHTSA on this investigation as we always do," a Ford spokeswoman told Reuters.

NHTSA often opens an investigation to determine if there is need for a recall of the vehicles involved. An investigation can lead to a recall but does not always.

One crash has been reported that is linked to the potential hazard, and no injuries, NHTSA said.

Federal officials did not say how many Explorer SUVs would be affected by the investigation.

The problem has been noticed, some Explorer owners told NHTSA, when the vehicle is at full throttle such as climbing steep hills, or when the air conditioning system is recirculating air into the cabin.

Ford in December 2012 and July 2014 issued two "technical service bulletins," which alert dealers' repair shops how to fix the potential problem. Some Explorer owners reported no solution to the issue after the repairs Ford Motor directed in the bulletins were conducted, NHTSA reported.