The National Highway Traffic Safety Administration has officially opened an investigation into 2010-'11 Mazda CX-9 crossover vehicles after a number of owners complained about brake booster failure.

"Complaints allege experiencing incidents of the brake pedal suddenly feeling hard, requiring increased effort to stop the vehicle," NHTSA said in its summary.

Approximately 62,319 vehicles are affected by the probe.

Federal safety regulators have yet to confirm if any crashes, injuries, or fatalities have occurred as a result of the issue.

"Complaints allege symptoms indicating possible loss of power assist to the brakes, including hard pedal, increased effort and reduced brake effectiveness. Several allege hearing a hissing noise during brake application," said the NHTSA.

The Mazda CX-9 has yet to be recalled at this point.

"We are indeed aware of the investigation, and we're fully cooperating with NHTSA in the matter," said Jeremy Barnes of Mazda, according to Edmunds.

Even though the NHTSA has just opened what it has called "a preliminary evaluation" into the issue, such a move often results in a recall.

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