Loss of power brakes. Excessive brake pedal pressure needed to stop vehicle. Hissing noise when depressing brake pedal.

- Monroe Twp, NJ, USA

I was approaching an intersection where I needed to stop with my children in the car, I went to hit my brake pedal and it was stuck in the up position and I couldn't stop, I had to quickly turn my wheel to hit the shoulder of the road to slow down and to avoid being hit in the intersection. The car brake then eventually released after hearing a hissing noise and it slowly going into the down position. When I had a mechanic look at it, he explained that it clearly is a failure of the brake booster. We researched it and found that similar issues happened with my make and model in the past but Mazda does not want to honor the defect as its special service call on it ended in 2015.

- Sellersville, PA, USA

Brake booster failure, causing brakes to not engage without pumping the brake pedal. No check engine or maintenance lights were triggered due to the failure. Only indication was engine revving while idle for no apparent reason and inability to bring the vehicle to a stop.

- Kyle, TX, USA

Uninformed about the 2011 Mazda CX9 brake problem which did not show up until 8-22-2018, I was informed that while Mazda extended their warranty, the warranty had ended in 4-2018 or when the car had 90,000 miles logged. (my car is at 91,244 miles.) the car is unsafe to drive, the brakes are suddenly not working, and this is a documented problem with my make, model, and year. There is no more important safety feature in your car than the brakes. Yes, teenage drivers ' that's even more important than bluetooth connectivity. Unfortunately, owners of the 2010-2011 Cx-9 have been having problems bringing their car to a stop. The brake symptoms Cx-9 owners, especially those in hotter climates, have been telling harrowing tales of brake problems centered around: The brakes became hard to push, there was a hissing noise from the pedal and the car would not stop until the brake petal was pumped.

- San Pedro, CA, USA

Brake peddle stiff, makes hissing noise. At times while in traffic loss of braking ability happens.

- Frederica, DE, USA

The brake start losing power and need to push really hard to stop.. and also make losing air sound when push on brake

- Brooklyn, NY, USA

Current mileage: 125707. Noted brake fade, insufficient braking response during normal city driving. The vehicle was towed to a location to have the brakes examined. New front rotors, calipers and brake pads were installed. Brake system bled and vehicle test driven. Normal braking during speed tests of city driving and emergency braking. Vehicle then driven for 2-3 days of normal operation. Operator driving the vehicle and when braking to a stop on approach to an intersection noted the brake pedal went to the floor before vehicle would slow. The pedal had to be pumped to obtain a measure of brake response. The vehicle took longer to slow to a stop. Also noted during braking was a "hissing" noise when depressing the pedal. Pedal was then pumped up on approach to any anticipated stopping point. Vehicle taken to be checked for possible air in the brake lines. Brake system checked for air in the brake lines and none found. Taken to a third-party shop for analysis. It was determined that the Mazda oem power brake booster had failed and per the mechanic (note attached pdf) the diaphragm had become "brittle" and the brake power booster failure caused the "hissing" noises and the brakes to be causing the brakes to become unresponsive. The oem brake booster had to be replaced. During a review of online information it was discovered that the NHTSA had conducted an investigation into the issue of master brake cylinder leakage regarding this generation of Mazda brake boosters. The vehicle has been in to a Mazda dealership for prior recall replacement of other defects, however this potential defect was not addressed.

- Bryson, TX, USA

My brakes did not respond as they normally would upon application of the brake pedal when approaching an intersection on Thursday morning. It felt almost like there was a pillow under the brake pedal. This occurred once on Thursday morning, and once on Friday afternoon. Friday evening brake fluid was filled to ensure that there was not a lack of fluid causing the problem, however the problem again occurred several times on Friday evening after adding brake fluid. By Saturday morning it was worsening both in frequency (occurring with every application of the brake) and severity (felt as though no matter how long and hard I applied pressure to the brakes it would not perform in a manner that would be effective in anything other than very slow speeds with excessive space between all vehicles). On Saturday it also began making a hissing noise which occurred as I was depressing the brake pedal, then stopped when the brake pedal was finally fully depressed (which took an extraordinarily long time). I felt it was no longer safe to drive other than to get it to our mechanic which I did on Monday morning. Our mechanic tested it and determined that the brake vacuum booster had failed and had to be replaced.

- Addison, MI, USA

Notice while on line for gas, maintaining foot on brake pedal car began to move forward and had to apply more foot pressure. Car has 690000 miles and over 7 years old. In park while depressing the brake pedal can hear a hissing sound. Symptoms getting worst, braking distances are longer and takes more pedal pressure.

- Sierra Madre, CA, USA

The contact owns a 2011 Mazda Cx-9. while driving at an unknown speed, the brakes failed to respond when the brake pedal was depressed. There were no warning indicators illuminated during the failure. The dealer was not contacted. The vehicle was taken to an independent mechanic where it was diagnosed that the brake booster failed. The vehicle was repaired. The manufacturer was notified of the failure. The VIN was unknown. The failure mileage was 120,000.

- Houston, TX, USA

The contact owns a 2011 Mazda Cx-9. while driving 40 mph, the brake pedal was depressed, but was extremely firm. The contact stated that gradually the brake pedal traveled to the floorboard before the vehicle was able to be stopped. The vehicle was taken to cardinaleway Mazda-peoria (8424 w bell rd, peoria, AZ 85382, (623) 738-0755) where it was diagnosed that the brake booster and brake booster switch needed to be replaced. The contact stated that the vehicle was currently at the dealer to be repaired. The contact stated that the failure was intermittent. The manufacturer was notified. The approximate failure mileage was 74,000.

- Phoenix, AZ, USA

Lost braking power. Pedal has to go to floor to work.

- Westminster, CO, USA

Brake booster failure brake pedal hissing and started to stiffen I was driving then stopped at a traffic light noticed that the brakes were hissing and was really hard to push on to a complete stop

- Fresno, CA, USA

Sitting at a stoplight, my brake pedal came up and the car died. Restarted it, and it ran fine. Happened again at a stoplight. I took it to a shop who said it was a "Mazda" issue. Within a week, my brakes started to not work. I took it to Mazda & they told me I was past the 90,000 extended warranty. I asked them why they wouldn't honor fixing it when it was a Mazda issue and they just said I was past the warranty. Beware of buying a "certified used car"! warranties/recalls will not be sent to you!

- Duvall, WA, USA

The contact owns a 2011 Mazda Cx-9. while driving, the brakes were applied and failed to respond. Additionally, the brake pedal became hard to depress. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was 60,000.

- Greenacres, FL, USA

Stiff pedal. No brakes

- Deer Park, CA, USA

My cars brake pedal suddenly became stiff and would not stop my car. I had to swerve to prevent myself from rear ending the vehicle in front of me. At the next stop light I was extremely cautious and after I finally stopped, as I waited for the green light the car began idling oddly then it stalled. Was able to start it back up. It seems to be shifting a little oddly too. Very scary driving my car. Incredibly lucky we weren't injured nor was anyone else. Will have it towed to the shop to be safe.

- Pacifica, CA, USA

The contact owns a 2011 Mazda Cx-9. while driving approximately 30 to 40 mph, the contact engaged the brake pedal and attempted make a left turn, but the brakes failed to engage. The contact was able to steer the vehicle onto a dirt road to bring the vehicle to a stop. The vehicle was towed to the Hyundai Mazda dealer (14821 pandelli road victorville, ca 92392 phone 760-241-3801) where it was diagnosed that the brake booster failed. The manufacturer stated that the brake booster failure was not warranted for 90,000 miles. The vehicle was not repaired. The failure mileage was 90,000.

- Apple Valley, CA, USA

Had a problem a few years ago related to the traction control system as indicated by the warning light appearing on the dash. Dealer contacted the warranty department to file a claim and said that is would not be covered under warranty because they felt it was due to dirt and not a faulty sensor. The dealer never confirmed one or the other. Second issue is related to a hissing noise coming from the break peddle. Research suggested Mazda was investigated by NHTSA back in 2014 and instead of a recall, Mazda issued and extended warranty for 7 years or 90K miles. Unfortunately my vehicle is within the 7 years but not the 90K. I am currently at 97K miles. Still waiting to see if Mazda will cover the repair or at least discount it.

- San Diego, CA, USA

While driving in the city or on highway suddenly the brake pedal becomes hard to press and creeps down to floor with loss of brake booster, a hissing noise is heard in the car and it becomes very hard to stop the vehicle

- Boson, MA, USA