Ford and federal safety officials are investigating reports of exhaust in certain SUV models after the automaker received around 20 complaints of carbon monoxide in the passenger side of vehicles. A customer has also filed a lawsuit, The Wall Street Journal reported.

In a lawsuit filed last week in Florida, customer Angela Sanchez-Knutson said that a test of her 2013 Ford Explorer revealed a high level of carbon monoxide in the cabin. More than 100 parts per million of carbon monoxide, a level 10 times higher than that found in ambient air, could allegedly accumulate in the Explorer's cabin while rear air conditioning was running. A level above 70 parts per million can become a health risk. 

Ford hasn't yet labeled the alleged high carbon monoxide levels a safety issue or initiated a recall. The carmaker sent a "technical service bulletin" related to the problem to its dealers in 2012, telling them how to fix an exhaust smell problem in vehicles.

According to Sanchez-Knutson's legal counsel, Ford's recommendations didn't remedy the issue in her Explorer.

"The fixes that the technical service bulletin recommends were all done to this car and it didn't fix the exhaust smell in the car," said Michael Hersh, the attorney representing Ms. Sanchez-Knutson. "They still smell exhaust," he said.

Her suit demands that Ford recall and repair the vehicles and seeks damages along with class action status and other conditions.

The National Highway Traffic Safety Administration hasn't begun a formal investigation of the issue but said it "is aware of the complaints involving 2011-2014 Ford Explorers" and "is reviewing all available data and will take appropriate action as warranted," as quoted by WSJ.

After two years of investigating, the agency has closed a probe into problems with power steering in late-model Ford Explorer vehicles, citing the carmaker's decision to recall nearly 200,000 Explorers from the 2011-'13 model years, Bloomberg reported.

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