The National Highway Traffic Safety Administration (NHTSA) is investigating a potential brake defect in model year 2010-2011 Mazda CX-9 vehicles. This investigation affects more than 62,000 2010-2011 CX-9 vehicles.
The NHTSA's Office of Defects Investigation (ODI) has identified 7 consumer complaints alleging incidents of unexpected loss of power assisted braking involving the Mazda CX-9. Complaints allege experiencing incidents of the brake pedal suddenly feeling hard requiring increased effort to stop the vehicle.
ODI previously investigated brake master cylinder leakage in model year 2008 Mazda CX-9 vehicles. Mazda identified a manufacturing process concern with the master cylinder primary plunger surface finish that may result in leakage from the master cylinder into the brake booster. Analysis of the complaint data found that the master cylinder leak condition was generally detected by illumination of the brake malfunction indicator lamp and identified only 9 reports alleging any effect related to brake pedal feel or brake effectiveness.
The investigation was closed on April 9, 2012 based on the extremely slow leak rate associated with the master cylinder condition, the declining failure trend, and the low probability that the condition could affect brake performance.
In contrast to the previous investigation, the complaints involving 2010 and 2011 Mazda CX-9 vehicles allege symptoms indicating possible loss of power assist to the brakes, including hard pedal, increased effort and reduced brake effectiveness. Several drivers allege hearing a hissing noise during brake application.
ODI has opened a Preliminary Evaluation to assess the scope, frequency and safety consequences relating to the alleged defect.