NHTSA Ends Probe of Porsche 911 Coolant Leaks By Stephen Elmer Mar 13 2014 Share this Article Tweet The National Highway Traffic Safety Administration has closed an investigation into 24,000 Porsche 911 vehicles, saying there is no need for a recall. Continue Reading... Filed under: Car Recalls Featured Articles German PorscheTags: porsche 911 coolant, Porsche 911 coolant leak, porsche 911 problems, Porsche 911 recall