Some 2010-2015 Mazda CX-9 vehicles may exhibit an unusual rattle/buzzing noise from the pre-silencer when driving at about 1,800 rpm
The lower (rear-side) of the pre-silencer may be thermally deformed due to insufficient rigidity (fewer weld spots). The deformed portion may resonate exhaust gas pulsations, causing the noise.
A reinforced plate has been added to the pre-silencer to increase rigidity. Replace the pre-silencer part number (P/N) CA11-40-300C, along with gaskets AJ17-40-305 and FSB8-40-305.
About the Author
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Information for Technical Service Bulletins comes from ProDemand, Mitchell 1's auto repair information software for domestic and import vehicles. Headquartered in San Diego, Mitchell 1 has provided quality repair information solutions to the automotive industry since 1918.
Mike Mavrigian
Motor Age Editor
Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.