In June, I noticed that when I stepped on the brake pedal, it would make a hissing sound, like air being released from a tire. Recently, the brake pedal feels soft and I have to step on it all the way for the car to slowly slowdown. Been in very close situations recently. I checked the brake fluid and it was low, so I refilled it and took it out for a drive... this did very little. The brake pedal still makes a hissing sound and feels very spongy. It is now making a brand new sound too. When I step on the brake pedal all the way, it makes a whistling sound. Very high pitch whistling sound like a lot of air is trying to squeeze out of a tiny hole. If this is a common problem, they need to get this car recalled because I use it to Transport my little ones around.

- Fresno, CA, USA

I was driving home from work today. When I approached a traffic light, I depressed the brake pedal and had to press it very hard for the car to stop. Good thing there was nobody in front of me because I would have hit them. As I started to go again and proceed to another light, as I pushed the brake pedal, I heard a 'hissing' sound coming from the pedal. It almost sounded like air coming out of a tire. This was alarming to me because I felt as if my brakes were giving out. I had to press very hard on the brake and as it braked, it was so sudden it shoved me forward in the seat. I took it right over to our service shop in town, and after he took the car for a test drive, he drove it right back and proceeded to tell me that it sounds like the brake booster was going. He advised me not to drive the car and to call aaa and have it towed to the dealer. I managed to get it back home, very slowly, and into the garage. This is very frightening to me because my daughter also drives this car on occasion and what if the brakes failed while she was driving?! in reading all the posts with customers having this same issue with the brakes, I think Mazda needs to recall this part before they have a bigger lawsuit on their hands! I will be calling the dealership first thing tomorrow morning.

- Suffield, CT, USA

Upon starting car and putting car into drive, brakes would not stop the car initially and had to pump the brakes several times to eventually keep the car from rolling. When the brakes are pressed to the floor, there is a high pitched squealing sound as if there is a vacuum leak or something. I suspect that based on the other complaints and articles I have read that the brake booster has a compromised seal. This needs to be a recall item and very soon as many peoples' lives are being put in danger because of this common defect in the CX9 family of braking systems.

- Yulee, FL, USA

Just after shifting into drive from park, noticed high pitched squeal and hissing. Brakes had to be pressed all the way to floor in order to stop the vehicle at only 5-10 mph. Then while driving sometimes brakes seemed to work fine and other times needed to depress brake pedal all the way to floor. Seems to be an issue that should be recalled given so many people having such an issue at low mileage.

- Glendale, WI, USA

I reversed my vehicle into a parking spot and started hearing abnormal noise like brakes grinding, but was still present even when not moving. Having a car backround I knew it was more like air. Wasn't sure what it was, but because I already work at a dealership I decided to have one of my diagnostic techs check it out. He knew right from my description that it was probably brake booster related. Called my dealership that always services my car for an emergency drop off. Bringing the vehicle to the dealership, every time I braked the pedal would not go down all the way, go straight to the floor, or I'd have to double tap the brakes similiar to if I was driving on ice. When at stops I'd hear the air noise from the booster, and even when the vehicle was off the pedal goes to the floor. Sometimes I'd be coming to a stop and the brakes would grab suddenly and I'd slide forward on the seat & most likely into the steering wheel if I didn't have my seatbelt on. The problems with the brake happened at sudden stops, slow stops, and the noise of air was present at all braking. Check online for tsb brakes for my vehicle and see it is becoming a common thing. Vehicle is at the dealership currently & is out of warranty, but with this being such a well noted concern & other issues I've had I don't know what I will do.

- Jackson, NJ, USA

Brake pedal became difficult to depress and vehicle also difficult to stop. Didn't take but a quick search to find many other owners of these vehicles experiencing the same thing based on their descriptions. It's so common it should already be a recall. Mazda should learn from other manufacturers mistakes and be proactive and not reactive. We already regretted purchasing the vehicle and this solidifies are decision to trade it in and never purchase a Mazda again.

- Schertz, TX, USA

Pulled out of my driveway this morning and tried to use my brakes -- heard a hissing, squeaking sound and the car didn't stop. I pumped the brakes several times was able to slow the vehicle down. Brakes felt extremely sluggish for the rest of my morning drive (dropping off my daughter at her school). At a stoplight the car stalled, which has never happened before. Took it to my mechanic who said the computer was kicking out multiple codes which seemed to be related to the brake booster system. He recommend I take the vehicle to a local Mazda dealership B/C it might still be under warranty. The Mazda dealer just confirmed that the problem is related to the supposedly known faulty brake booster system and a leak in the vacuum. Mazda will replace the parts for free and not charge any labor, either. Very scary issue -- I nearly hit several vehicles on my drive this morning and was lucky that the cars in front of my moved to avoid an accident. Mazda needs to recall all cars with this issue before someone is injured, or worse.

- Los Angeles, CA, USA

At varying speeds, the brakes are very difficult to apply. When applied fully, a loud squealing can be heard from the dashboard area. The vehicle is currently at a service center for evaluation.

- Port Richey, FL, USA

Vacuum leak on brake booster. Can hear the leak when depressing pedal. Becomes very hard when depressed fully and is hard to stop, this is a well documented problem.

- Gold Canyon, AZ, USA

Attempting to stop the vehicle at a red light, brake pedal was hard to push, increasing the distance required to stop the vehicle. This has happened multiple times, along with a hissing sound coming from the drivers side of the vehicle when the brake pedal is depressed. We are still having problems with the brakes and have scheduled a service with Mazda.

- Kissimmee, FL, USA

While I was driving this SUV with my family( wife, 4 year old son, 2 yr old daughter), breaks were sticky and not applied. I was about to hit across the vehicle but luckily I stopped by using emergency breaks and moving shift rod to L. I spoke to Mazda dealer and he told me that it is a break defect and Mazda will cover for it. This is very serious incident and do not want to happen to others. By god grace we survived. I can feel my death during that time. Thanks [xxx] information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6).

- Katy, TX, USA

Brakes pedal becomes hard and either impossible to push or goes only half-way down. As a result car doesn't come to a full stop. This happened at least 3 times during last week, until I took it to a dealership and they replaced the brake booster. I found that this is known issue for 2010 and 2011 vehicles and there was an investigation about it and investigation was closed around July 2014 without any recalls. But seems like the same problem exists for 2012 models as well and Mazda didn't fix it on newer models.

- Kirkland, WA, USA

For the past week, my 2012 Mazda Cx-9 has been having issues with not braking. At first, I thought it was just my imagination, but every day this pas week, at least once a day, I go to push on the brake pedal and it won't move. The brake pedal is stiff as if I'm pushing on a block of cement. It's very scary, and I've almost hit several cars, and even almost hit a pedestrian. I am a mom and drive with my small children in the car often. That's why I bought a family vehicle. Today I was at a drive thru window, and the car stalled completely. I turned the ignition, and it started up, but the engine was shaky, not idling right. It felt like it would stall again at any moment. I called Mazda, but my car has 40K miles, and they were very rude and said my warranty expired at 36K miles. I took it to our family friend who is a mechanic, and when I told him about the brake problem and the stalling, he said he knew exactly what was wrong. There was a leak in the vacuum system on the brake booster, and the stall and the brake problem are both caused by that. I went online and did research, and found this site, and that others are having this problem. I called Mazda back and got he same rude service guy. I explained what I had found on this site, and he said, well this morning when you called, you only told me about the stall, you didn't tell me you were having braking problems. He acknowledged that there was a problem with the brake booster and checked my VIN to be sure my car was covered under the newly extended warranty on the brake booster. I'm taking it in tomorrow for them to repair it free of charge. This is extremely scary and I hope the NHTSA will do a recall on this!!! myself or my family could have been severely injured in an accident, or I could have injured someone else!!!

- Rancho Santa Margarita, CA, USA

We were traveling 60 miles to work when my husband noticed that the brakes were not functioning properly. They became very hard to press down and slow to stop. We immediately took it into a mechanic off the freeway who inspected the vehicle and told us that he had never seen anything like it. We needed to take it back to the dealer. The power boost had failed. We had it towed to the Mazda dealer who informed us that it was on recall. We did not receive a recall notice nor did we know about this. We are lucky to be alive the distance that we had to travel. The dealer also told us to call a Mazda towing number as it was on recall - but even tho the car is only 2 years old - they said it had too many miles to be towed for free.

- San Clemente, CA, USA

While moving at approximately 20 mph in a normal driving profile on a clear day 73 degree day with no precipitation, I attempted to slow and stop the vehicle progressively utilizing the brake system on the vehicle. I was unable to stop at my intended point and drove past the stop sign; approximately one half car length forward of the stop sign and into the intersection. Following the event, the feedback from the braking system thorough the brake pedal felt hard and the system was extremely unresponsive. In subsequent stops the same afternoon, I was forced to double my braking distance and car length to account for the braking systems unresponsiveness. In the event I was required to conduct a hard stop at high speed, it is unlikely I would be able to stop the vehicle in the condition I experienced 9/12/14. After speaking with another driver of the same vehicle, this event (while more severe) has become a common occurrence over the last 2 weeks. That is; an unresponsive brake system accompanying varying degrees of braking system failure resulting in unpredictable vehicle behavior and poor stopping capability. Mileage 19384.

- Meridian, ID, USA

On 8/29/14, my car would not stop and continued to move when I pressed on the brakes to stop at a traffic light, almost hit the car in front of me. Scary! again at the next stop sign, the car continued without stopping when I pressed on the brakes. Mazda told me that my car is out of warranty so I went to a mechanic who replaced a defective master cylinder. A week later, my car stalled twice when I was stopped at a red light. Then the brakes "hissed" when I pressed on them. The brake pedal was very hard to press and the car would continue to coast even when the brakes were pressed. Scary for my children! the same mechanic called Mazda, and was informed that there is an extended warranty on a brake booster. I did not receive any such notice from Mazda. Mazda replaced the brake booster and brake switch today for free. Also note, the day I bought this car, brand new on Dec 2, 2011, I drove on the turnpike and realized the transmission was slipping. I took it back to Mazda and they replaced a defective turbine speed sensor on my car. Enough!

- Sicklerville, NJ, USA

Vehicle lost braking power. Vehicle was being driven (infant inside) from Chicago to evansville, in when brakes starting to respond in a delayed manner from when brake pedal was actually pressed. By next morning the vehicle did not brake. Mazda dealership checked the vehicle and mentioned that somehow master cylinder and booster failedwith no apparent reason as they were able to tell no abusive or incorrect use was applied to the vehicle. Mazda will replace parts that failed to work but it placed my family in a very dangerous situation.

- Newburgh, IN, USA

Like others, I have begun to experience significant problems with the braking system on my 2012 Mazda Cx-9. when depressed, the brakes make a hissing sound and it is very difficult to depress the brake pedal. Once depressed, there is a delay in bringing the vehicle to a stop which poses a significant safety issue. It is almost as if power has been lost in the braking system. Casually consulted with the gentleman performing standard maintenance (oil change) on the vehicle today. Brake fluid is full. To him, it sounded like a booster problem which, if other reports here are correct, sounds to be a good guess. A recall is in order.

- Wheaton, IL, USA

I've purchased 2012 Mazda Cx-9 AWD it late November of 2011.recently I've been experiencing multiple unexpected loss of power-assisted brakes failure incident.I was in a minor fender bendeer. Thank god the driver infront was very nice and didnt file any claim against my insurance. When I brought my vehicle into Mazda services department to get it resolve. Instead of taking unexpected loss of power-assisted brakes as an urgent matter. They told me that my car is drivable and it still break. I can drive my Mazda in the meanwhile, until they have an open appointment for my Mazda to be seen. After speaking to multiple personel at the services department. They were able to take my Mazda and fixed the unexpected loss of power-assisted brakes. Now im experiencing speed control and power train. I was at a stop light and my Mazda stalled in the middle of a left turning lane, in addtion to the stall incident, I was also experiencing the traction control light came on and the tire pressure monitor light began to flash. It felt like car had downshifted a couple of gears. I lost forward power in all gears. My sons and I came close to multiple rear-ended incident because of the mechanical issue of our Mazda CX9. Please becareful when deciding to purchased your Mazda vehicle.

- Seattle, WA, USA

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