U.S. safety regulators have opened an investigation into warranty claims regarding the brake effectiveness of a 2008 Mazda Motor Corp sport utility vehicle.
The probe deals with leaking brake fluid that could degrade the brakes of 2008 model-year Mazda CX-9 autos, the U.S. National Highway Traffic Safety Administration said in a filing.
No injuries or crashes have been reported, the NHTSA said.
An estimated 37,000 of the autos could be affected.
A Mazda spokesman was not immediately available for comment.
The NHTSA said it had received data from Mazda covering a period from the first quarter of 2008 to the third quarter of 2010 indicating a "high number" of warranty claims and reports.
"When brake fluid leaks into the vacuum booster the driver can experience reduced brake effectiveness which can result in extended stopping distance," the filing said.
A preliminary investigation is the first step in a process that could lead to a recall if regulators determine that a safety issue needs to be addressed by a manufacturer.