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.

- Auburn, CA, USA

Brake master cylinder hissing and squealing while engine is in idle. After revving (and releasing) to 2000 RPM's and applying (holding) brake pressure simultaneously, the build up vacuum pressure does not allow engine to return to idle RPM. RPM hangs at 1500 RPM's. if vehicle is in drive while accomplishing this then the brake pressure applied is not enough to bring the vehicle to a stop. After find the cause of the issue I went online and found previous message boards about this issued were posted in early 2014 but a recall was never issued. Reported the issue to Mazda (20161012) but was told that since the vehicle is 30K outside of the extended warranty then the issue belongs to the consumer. (mazdaref 1-368-227-539).

- Fort Worth, TX, USA

As I was driving my car on a city street, I lost all steering and braking ability. The first time it happened - mazada thought it was a suction from the brake and a tube that was broken. However it just happened again as I was reversing in a parking lot. The car is now with mazada being looked at...

- Walnut Creek, CA, USA

Driving from work today on a highway behind an electric truck that stopped abruptly, I applied my breaks kind of quickly and after stopping and taking off again when trying to apply brakes to slow the peddle would be really hard to press and it felt like the peddle was pushing up against you. There is a hissing noise when brake is applied and if you press the brake all the way to the floor there is a squealing noise. The hissing noise is inside the care and sounds to be coming from around the brake peddle area. The car can not be drove at this time because when in movement the brake is really hard to press and it takes very long distances to get stopped. I can't put my children in this car to go anyplace!

- Maysville, KY, USA

There was a ratal sound anytime I would go over a bump or dip at any speed. The ratal got louder. I went to my mechanic and he said the calipers in the front had to be replaced. Specifically the driver's side it looked worn and there was rust so he thought moisture had got into the calipers. Thought this was unusal. So both had to be replaced in addition to my brakes. It also caused my brakes not to function correctlyl.

- Boise, ID, USA

Reference ssp93 - brake booster diaphragm leakage on 2010-2012 Mazda Cx-9 vehicles. On, or about August 5, 2016 power brakes failed, causing a need to apply heavier than normal pedal pressure to stop vehicle, resulting in very near rear-end collision with vehicle at stop sign. This defect is known by the manufacturer and was investigated by NHTSA in 2014. Investigation was closed with no recall action recommended. There should indeed be a recall mandated for this defect since it can result in serious collisions due to failure to safely stop vehicle.

- Angleton, TX, USA

Loss of brake fluid; brake pedal hard to push & not stopping car; noise at brake pedal

- Hampstead, NC, USA

Brakes resist when trying to stop, taking longer to come to complete stop(at any speeds). Once stopped brake compresses all the way down on its own, feels like the car will start roll. When applying brakes it makes an air decompression sound. When backing out of parked position and braking, car coasts a little when brakes are completely pressed down. Very dangerous issue that I realized was related to the extended warranty brake booster issue that I received earlier in the year. I attempted to get this repair at the first service I scheduled after receiving notice and Mazda service department refused to complete service because they didn't think my car needed it.

- Harrisburg, PA, USA

Brakes have suddenly become erratic. Often they are "hard" and require excessive pressure to get the vehicle to stop. My research shows this is a known issue with this year and model, and Mazda extended their warranty to cover the issue; however, that evidently does not apply to second owners.

- Seminole, FL, USA

There is an issue when using the brakes where there's a loss of power assist making the brakes really hard to push at times, a sudden loss of braking ability with super spongy pedals, and a strange, hissing noise coming from the pedal area. These issues happen concurrently when driving in the city or highway and whenever the car is in reverse or drive.

- San Diego, CA, USA

Brakes are making a hissing sound when you press down. The brakes are hard to push and the vehicle is not stopping properly.

- Centerville, TX, USA

The contact owns a 2011 Mazda Cx-9. while coming to a stop at 10 mph, the brake pedal felt squishy. When the brake pedal was depressed, the brake pedal would almost travel to the floorboard. The feeling was also present while the vehicle was stopped at a stop light. Three months later, the contact heard an air noise when the brakes were being applied. The vehicle was taken to a dealer where it could not be diagnosed; however, the failure recurred. The manufacturer was not made aware of the failure. The failure mileage was 80,000.

- Ocklawaha, FL, USA

Same issue as everyone else hissing when brakes are compressed -or car is stopped and bad or lagging in braking. My brakes were completely down to the floor and the car kept slowly trying to roll. I had to pump the brakes. Or put the car in park. When I let the brakes go no hissing

- Braintree, MA, USA

Brakes are not working properly or consistently. Sometimes have to press too hard on brakes and other times it works fine. Also, brakes are making a hissing sound like air coming out of tire.

- Cooper City, FL, USA

Several times when the vehicle is in motion, and the driver attempts to apply the brakes, the pedal seems unresponsive. During these incidents, the brake pedal is very hard to apply, nearly impossible. Thankfully when this transpired (5-10 times over the last 2-3 weeks), we were traveling relatively slowly. After exerting much more than normal force, the brake pedal seems to depress and help bring the vehicle to a stop, although not at the normal rate of braking. Additionally, during one of these incidents, which happened today, the brakes remained engaged, and the car would not move, even after shifting to park, and turning off the engine. Eventually, after shutting off the engine a second time and waiting awhile, the brakes released. This incident occurred while driving on city streets, and trying to stop at a red light. Most of the other incidents have occurred during city driving, but they have also occurred while driving on the highway as well.

- West Point, NY, USA

When breaking I hear a hissing noise and found out my break boaster was going bad.

- Enterprise, AL, USA

Hissing noise when pressing brake pedal. If feels like more force is needed to stop vehicle. Loud noise from transmission when shifting from part to drive/reverse

- Chicago, IL, USA

Hissing sound when applying brakes, brake feels stiff. Have an appointment tomorrow (they said it should be ok to drive until then), said it was probably the master cylinder failing.

- Newcastle, CA, USA

I have recently experienced trouble with my brakes. It has been very difficult to come to a complete stop no matter what my speed is. It feels like I have to push very hard to get the brakes to engage. Also, I hear a hissing noise, like air coming out of the tires when pressing on the brake pedal. No warning lights have come on. I took the car into just brakes last night and am waiting for an assessment. The mechanic said it sounded like a problem with the power boosters.

- San Antonio, TX, USA

When pressing the brakes at any speed there was a hissing sound and the brakes were hard to press. Regardless of the amount of pressure I applied to the brakes they did not react and it took the vehicle longer to slow down even at very low speeds (5-10 mph) or faster. This came on suddenly and caused me to bring the vehicle into the service department of the the dealership where I purchased it. The Mazda technician inspected the vehicles and completed a diagnostics of the vehicle and discovered that the master cylinder and brake booster have failed and need to be replaced.

- New Orleans, LA, USA