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2011 Mazda CX-9 brakes problems: hissing from brakes

Hissing From Brakes Seal Of This Might Hurt Notes: The only area of real concern for 2011 Mazda CX-9 owners is the brake booster.

In 2014, Mazda extended the warranty on the 2007-2013 CX-9 brake booster to 7 years / 90,000 miles. However this extended warranty has expired, so buyer beware.

This Mazda CX-9 brake booster failure isn't terrible in terms of repair cost — it "only" costs $550 average to fix. However it is a safety issue when the brake booster fails as it increases stopping distance. Owners have reported having to stomp on the brake pedal, & crashes/injuries have been reported due to this CX-9 brake booster defect.


pretty bad
Typical Repair Cost:
No data
Average Mileage:
88,200 miles
Total Complaints:
5 complaints

Most Common Solutions:

  1. not sure (4 reports)
  2. replace defective brake booster (1 reports)
2011 Mazda CX-9 brakes problems

brakes problem

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2011 Mazda CX-9 Owner Comments

problem #5

Jun 012017

CX-9 4WD V6

  • CVT transmission
  • 89,329 miles


This is a scary sound and issue to have in a car that I rarely drive!

I'm looking to get this fixed but found this website first.

- lcenova, Carmel, US

problem #4

May 282017

CX-9 4WD V6

  • CVT transmission
  • 89,321 miles

This is a scary sound and makes me feel very unsafe in a car I don't drive very often. I am looking to get this fixed and found this website.

- lcenova, Carmel, US

problem #3

May 012017


  • Automatic transmission
  • 78,000 miles

Brakes have completely stopped working. It was almost overnight that it happened I came close to getting into a really bad accident.

- Pamela T., Arnold, MD, US

problem #2

Nov 012016

CX-9 Limited 3.7L V6

  • Automatic transmission
  • 91,245 miles

A strange, hissing noise coming from the pedal area. I am having a hard time pushing the pedal during “initial pedal application”, but that effort diminished as the pedal was pressed further while driving. The brakes booster squeals very loud if you push the brakes down while not moving. I did some research and found this is a defective brake booster issue that Mazda had confirmed.

- William A., Auburn, CA, USA

problem #1

Oct 292016

CX-9 Touring

  • Automatic transmission
  • 93,000 miles

brake booster fails causing degraded braking and hissing

I bought this car about 2 months ago. I test drove it twice to make sure there were no issues with the brakes. Now less than 2 months after buying it I am having severe issues, including the notorious hissing sound and terrible braking performance where the pedal feels hard at first and then gets spongy.

I am taking it in for repairs on Monday and asked for a rough estimate. The dealer would not give me a number and said it "might" be covered under warranty. However, the car has 93,000 miles so I'm not expecting them to cover any of the repair costs due to the 90,000 mile warranty coverage I've seen referenced online.

The dealer was familiar with the brake booster problem and advised that I not drive the car unless absolutely necessary before the repair was done. If this is such a severe problem then Mazda should have issued a recall instead of leaving consumers to foot the bill if the car wasn't repaired before the 90,000 mile / 7 year warranty cut-off.

Shame on the NHTSA for letting Mazda off the hook by not requiring them to issue a recall and instead forcing consumers to foot the bill for what is clearly a design flaw that puts people at severe risk.

- Michael A., Riverside, RI, USA

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