Whiles driving and approaching a stop light or traffic light, the brakes depress and the car doesn't stop, the brakes have to be pumped but then then the brakes are hard/stiff so much so that you have to push really hard for the car to stop. Once this happens, it recurs all the time. The engine check light came on a day later, not sure if it related, I assume so for now. My car has less than 10,000 miles on it. I notice there is recall notice for this condition by Mazda but this is an extremely dangerous situation, which should be fixed at once. It seems to be a least effort type of recall notice for an extremely dangerous situation. To summarize, whiles driving your brakes fail and the car does not stop. When you pump the brakes, they are stiff / hard and you have to push down really hard for the car to stop.

- Brooklyn, NY, USA

The brakes have to be pressed very hard to stop the vechile.. there is a delay between the time you press the brakes and the time that the brakes actually start to slow the vechicle. You can also hear a hissing sound when applying the brakes.

- Minden, LA, USA

Brakes lost pressure, requiring significant increase in force applied to the brakes to bring vehicle to a stop. When brake peddle would be depressed, it would make a hissing type of noise.

- Saint Johns, FL, USA

Following up a previous complaint that brakes are hard and require longer stopping distance. I took the card to the dealer for a hissing sound the brakes were making and they said it was fine. I am taking my car back to the dealer because the problem has gotten significantly worse over the last month. I do not feel safe driving my car and I have less confidence in the brake system.

- Orlando, FL, USA

My brakes have started making a hissing sound and brakes are hard when pressed. I experienced a similar issue with a 2008 Mazda Cx-9 in which the master cylinder and brake booster had to be replaced. I now own a 2012 Mazda Cx-9 and am experiencing the same problem. I took it to the dealer May 14th, 2014 and they said it was fine. It now has gotten worse as of June 22, 2014, to the point the brake is very hard when depressed and takes several car lengths to come to a complete stop. Mazda needs to address and fix this issue with this model if they want to keep their customers. They did extend the brake booster warranty for this problem specifically but they need to correct and improve the brake system in their newer vehicles to maintain the safety for their drivers. I am already considering a different make and model for my next vehicle. I have always been happy with my Mazda but no longer feel safe driving it and feel dissatisfied having experienced the same problem in this model that are 5 model years apart. You would think they would do better to improve the brake system, a major safety feature for a family vehicle.

- Orlando, FL, USA

The contact owns a 2012 Mazda Cx-9. the contact stated that while traveling 15 mph, the vehicle exhibited difficulty in decelerating. The contact had to pump the break pedal extremely hard in order to slow the vehicle. There was a hissing noise that sounded throughout the vehicle. The vehicle did not decelerate until approaching an incline. The contact was able to stop at a local mechanic shop where the mechanic diagnosed the that the brake vacuum booster needed to be replaced. The vehicle was repaired. The failure mileage was 55,000.

- Dripping Springs, TX, USA

My wife complained about the brakes on her 2012 Mazda CX9 making a hissing type sound and brakes feeling different than normal. I have drove the vehicle and confirmed the power brake assist is not operating. We learned that others have had the same problem for 2010 and 2011 model year and nhtsb is investigating. There are at least seven complaints for 2012 model year with the same issue. Please include the 2012 model year in the investigation for this dangerous defect.

- Simpsonville, SC, USA

There was a sudden loss of power boost to the brakes, making it very difficult to stop the vehicle. This happened intermittently: Sometimes the power boost would work when the brakes were applied, sometimes not. I came very close to rear-ending the car in front of me the first time it happened. It happens without warning.

- Thousand Oaks, CA, USA

I have an issue with the brake pedal making a hissing sound when depressed, it fills soft and extremely hard, which makes it difficult to stop. If I release the brake pedal the engine revs up and down at least three times making the car hesitate with engine clunking and a feeling like someone hitting you from behind. It happens very sudden and unsafe manner. I had two occasions when a had to press extremely hard on the brake to stop the car. I think that there is a serious mechanical defect with the brake system and should be immediately addressed by Mazda. I had researched on line and there are number of Mazda CX9 owners with similar complain. Please feel free to contact me for further assistance with this matter.. sincerely. [xxx] [xxx] or home [xxx] information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6)

- Bronx, NY, USA

The contact owns 2012 Mazda CX9. The contact stated the brakes would hiss when being depressed. The contact also stated that there was an abnormal increase in braking distance and time. The vehicle was taken to the dealer for diagnosis, who stated that the brake booster and possibly the master cylinder would need to be replaced. The vehicle was repaired. The manufacturer was not alerted of the failure. The failure mileage was 35,000.

- Pampano Beach, FL, USA

At approximately 25,300 miles, my 2012 CX9 touring started stalling at traffic lights. It was sporadic, but appeared to happen when I used more force when braking. Within days I noticed a very distinct hissing sound while braking, much like air was leaking from my tires. At this point, braking became increasingly more difficult, and the distance required to stop my car was much greater. I almost had a collision because I did not realize I needed to begin braking sooner in order to stop my car and I veered into a grassy median to avoid the accident. In order to stop the car I had to apply both feet to my brake pedal and it was nearly on the floor. The service advisor said this was a safety issue and found the "brake booster failing internally", and it was replaced. The stalling was due to "vacuum leak through booster". there was no indication that my brakes had a problem; no dashboard mainteance lights were present. This is a serious safety issue. I just read about a current brake booster failure investigation with 2010 and 2011 model years, but 2012 needs to be included in this investigation as well.

- Lithia, FL, USA

The brake assist booster on this vehicle failed. This is the same issue cited in a National Highway Traffic Safety Administration investigation of the 2010-2011 Mazda CX9 vehicles.

- Morgantown, WV, USA

Brakes not working properly, reduced brake effectiveness, hard pedal and not stopping properly, and a definite constant hissing when applying the brake pedal. Possible master cylinder issue. Mazda CX9, 2012. Very similar to complaints and ongoing investigation, except for this is a 2012.

- Friendswood, TX, USA

I am unsure of the first date of occurrence, but the following have been happening since I purchased this vehicle new with 12 miles on it. And the dealer can't find anything wrong with it. 1. the ac always comes on. Even when it's below zero outside. 2. it fails to go when pushing on the accelerator frequently, and especially in reverse, from a stopped position, until you really push hard on the accelerator causing it jump. 3. last Friday 2/21/2014 as I was on a ramp moving from one interstate to another, the engine continued to rev up even after I let off the gas, and pushed the brake. This is not the first occurrence of this, it's actually happened at least 10-12 times. It was definitely the most scary, as I thought I was going over the side of the ramp or into the semi in front of me for a minute or so. 4. the brakes squeak loudly when it's cold. 5. the brakes are either really sensitive, or you have to stomp them to get them to work, so since you don't know which it's going to be you're likely to jerk yourself and your passengers around a lot. 6. the vehicle pulls to one side or the other, which would seem to indicate that an alignment is needed, however, it can't pick which side it's going to gravitate towards which leads me to believe it's something in the steering.

- Greencastle, IN, USA

Total brake failure.

- Muncy, PA, USA

I have a Mazda 2012 that spontaneously stalls while decelerating. It also stalls predictably on an incline. Mazda corporation has stated "the stalling on an incline is a characteristic of all Cx-9 models" and are not willing to fix it. They have informed me that stalling while decelerating in my car has not been able to be recreated by their tech so they are doing nothing about it. I have been in two near miss accidents. The car loses power steering and braking and the driver has little to no control when it stalls. Please watch this video of a brand new (loaner from the dealer while they looked at my 2012 Cx-9) 2013 Cx-9 (125 miles on it). This is the "characteristic" I am referring to, please advise future buyers of this very unsafe "characteristic". when it stalls in my driveway, I cannot brake "sharply" or effectively enough to stop the car from drifting into the road. youtu.be/pbzhvieihkc.

- Andover, NJ, USA

Incident -1 traveling about 45 mph decelerating to make a right turn, the car stalls out leaving me with no control of steering and little ability to brake. Incident 2- making right turn (decelerating) car stalls out leaving me with no steering and little braking control. Incident 3- pulled up into driveway on slope. Put the car in reverse to back out, car stalled out leaving me with very little ability to brake.

- Andover, NJ, USA

Our 2012 Mazda CX9 sport fwd lost all brake boost on several occasions. My wife complained the vehicle would not stop when backing. I drove the vehicle and I was only able to stop the vehicle after significantly increasing pressure on the brake pedal. The Mazda dealer advised it was indeed the brake booster. This is a serious safety issue and needs to be addressed by Mazda and NHTSA. Our vehicle was less than a year old with less than 10000 miles at the point of failure.

- Leander , TX, USA

I had an incident yesterday resulting in a minor collision. My accelerator stuck, my engine kept revving, and I could not stop. I kept applying the brakes but it felt as if everything locked up. I rearended the person in front of me no damage to their car and only minor to mine. I am now afraid to drive the vehicle. My husband contacted the dealership and they are waiting to hear back from Mazda corporate.

- Dayton, NV, USA