After a number of complaints and a federal lawsuit, the National Highway Traffic Safety Administration is reviewing exhaust leaks in Ford Explorer SUVs.

In a statement, the government agency says it has received complaints from owners of Explorers from model year 2011 through 2014 that describe exhaust fumes or other odors permeating in the vehicle’s cabin. “The agency stopped short of calling its effort a defect investigation, and no formal probe is listed on its Web site,” Bloomberg and Automotive News reported.

NHTSA’s review, however, was only announced publicly Friday, several weeks after Angela Knutson, the owner of a 2013 Ford Explorer, filed a lawsuit in Florida federal court. The suit alleges that her SUV was among thousands of others that had a defect that could cause “lethal quantities of carbon monoxide” to enter the passenger cabins, according to Delhi Daily News.

Knutson is seeking the class action to represent owners of Explorers from model years 2011 through 2013. Her lawsuit alleges that Ford knew about the issue, having sent a technical service bulletin to dealers to advise that Explorers from model years 2011 to 2013 “may exhibit an exhaust odor in the vehicle with the auxiliary climate control system on.”

Ford was reviewing Knutson’s case and other complaints and would take necessary action, according to Ford spokesperson. The NHTSA, in its statement, said it was “reviewing all available data and will take appropriate action as warranted.”

“We are confident in our current methods for quickly identifying and addressing potential vehicle issues,” Ford spokeswoman Kristina Adamski told Automotive News. “Our decisions are driven by the data available. When the data indicates a safety recall is needed, we move quickly on behalf of our customers.”

The NHTSA has recently closed a 2-year-old investigation into late-model Ford Explorer power steering issues, which culminated after the Detroit automaker recalled nearly 200,000 Explorers from the 2011-13 model years.