While driving in houston highway rush hour traffic attempted to apply brakes due to traffic stopped ahead. Brake pedal was very difficult to press and made a hissing noise. After about 20-30 yards was finally able to bring car to a stop narrowly avoiding an accident. When took vehicle to Mazda dealership was told it is the power brake booster that needs to be replaced. Service tech stated this was a known issue with the 2010 Cx-9's. Mazda issued an extended warranty but customers were never notified so they could get the defective part repaired. My vehicle only has 83600 miles, so it is average mileage for an 8 year old car.

- Friendswood, TX, USA

Started getting a hissing sound from the brake booster and a hard to depress brake pedal.

- Allentown, PA, USA

Hissing sound near brake pedal followed by extremely hard pedal and much effort to stop.

- Raleigh, NC, USA

The contact owns a 2010 Mazda Cx-9. while the brake pedal was depressed, the vehicle came to a slow stop. The contact heard a hissing noise coming from the brake booster. There were no warning indicators illuminated. The vehicle was taken to ed morse bayview Cadillac (1240 N federal hwy, fort lauderdale, fl 33304 (888) 463-2950) where it was diagnosed that the brake booster needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and did not offer any assistance. The approximate failure mileage was 100,000.

- Coral Springs, FL, USA

Mazda Cx-9 when applying the breaks, pedal at one point during breaking process becomes spongy, as pedal resistance appears to release. When foot pressure is removed from break pedal and reapplied, break pedal pressure is very hard to press and breaking efficiency is diminished considerably as though break booster has failed. Breaking issue appears to occur primarily when coming to a stop at reduced speeds. Noticed issue with recent ca heat wave, vehicle appears unsafe to operate. With wife participating as a driver in carpool, she just recently experienced the condition and is concerned that it can result in an accident if not addressed. Certainly appears to be the same issue indicated here: www.carcomplaints.com/news/2014/government-closes-Mazda-Cx-9-brake-pedal-investigation.shtml

- Carlsbad, CA, USA

My brake pedal suddently became very hard to push, lets off a hissing sound when pushed and takes a long time to stop. I was on a city street coming to a stop light and wasn't sure my car was going to come to a stop. I am now learning through research that this was a problem Mazda knew about but didn't notify everyone of the extended warranty they offered to make the necessary repair. Now, my car doesn't qualify for the repair as it isn't in the limited extended warranty mileage that Mazda offered for this repair. I just started having problems with this issue on Sunday, August 20, 2017. Since I never received any notice of this brake booster problem, how could I possibly have known about the extended warranty and had it serviced during that time and mileage frame?

- Fayetteville, GA, USA

My brake pedal becomes very hard to push, lets off a hissing or whistling sound when pushed and takes a long time to stop. When I called the dealer they advised it was a known break booster issue. The issue happens maybe 1/4-1/2 of the time I am trying to break. The dealer had me bring the car in- but then told me my car didn't qualify for the repair as it wasn't in the limited extended warranty mileage that Mazda offered for this repair. My complaint is - if this is a known safety issue with the breaks not working properly- why is this not a recall and just a limited warranty- how can they get away with that? also, how can they then not notify all the owners of the potentially affected vehicles of the limited warranty so that we can bring the car in at that time for repairs- instead of only waiting until a customer has a complaint on the issue.

- Newton, NJ, USA

My brakes have a hissing noise and and are hard to brake when I push the brake pedal. The service dept tells me that the brake booster is bad and needs replacement. ($800)these are supposed to last the life of the car. I have just over 100, 000 miles on it. I have a 2010 Mazda Cx-9. I was never notified that Mazda had this widespread problem, that the government was investigating it, or that Mazda was offering a "special service program" that would have covered this repair while it was under 90,000 miles. It was in motion when I I noticed this problem last Thursday while driving on city streets. It is now in shop.

- Kansas City, MO, USA

Took my car to dealer 2-3 times for the brakes, way before my warranty was any where near expiring, because I kept hearing a grinding sound. They kept telling me nothing was wrong, that my brakes had some gravel on them and they just cleaned them. I don't travel on dirt roads or anything, city roads/highways. No out of town travel at all, actual only in town travel, home/work. My 2nd concern is, while driving sometimes my speed seems to shift, as if the gears are shifting. 3rd concern is, I received a recall notice, don't recall what it was about but I took it to the dealership and I was told they done that work last time I came in but I don't believe it was done, since they haven't been honest with me before. They didn't even look at the letter. If I recall correctly brake complaints/ service started 2011 or 2012 to 2014....

- Little Rock, AR, USA

Suddenly had trouble braking, difficult to push the brake down and started to make a hissing sound. It was an uneasy experience and luckily my kids weren't in the car.

- Ellicott City, MD, USA

The brakes on our 2010 Cx-9 are hissing upon brake engagement and have a hard feel to them for the first half or so. The brakes are slow to engage during this time. After the half way mark the brakes engage quickly and forcefully. It is consistent with the other complaints for the brake booster failure. I am having it looked at this week at a Mazda dealership.

- Bountiful, UT, USA

Poor braking which Mazda recognized as a brake booster and master cylinder problem but never notified its Cx-9 customers to go to the dealership to have the repair done.

- Churchton, MD, USA

2010-11 Cx-9 brake booster failure. Rapid onset from first symptoms to complete failure braking occurred within 45 minutes of driving on heavy interstate congested traffic during rush hour. Breaking failure is most significant if breaking is first applied lightly as a cautionary measure. Applying light breaks results in breaking system pressure to rapidly drop disabling assisted breaking within a few seconds. Breaking a heavy vehicle with fail power assist almost always resulted in either insufficient braking, or wheel lockup. (note, ABS fails). The assist braking then returns if brake is release for more than 10 seconds providing the brake is not applied. This is a significant safety hazard that may easily result in the destruction of property and death. The defect seems to have been glossed over by the NHTSA in April 2014 when the NHTSA investigation into this failure was closed. It appears that the investigation was closed when Mazda elected to use standard us mail to inform affected Mazda owners that it was 'extending its service warranty' by giving customers 1 year from notice to have the defective part replaced. If the Mazda owner did not receive or act upon the 'extended warranty' within the following 12 months and the brake booster failed, the customer would be responsible for over $1000 in repair costs, serious property destruction or even death. It is shameful that the NHTSA closed it's investigation so quickly on account of such remedial action by Mazda corporation.

- San Mateo, CA, USA

Brake booster failed, dealership indicated it was under extended warranty. Brought in for repairs at no cost, Mazda failed to acknowledge and do repair. Cost me $556.21 for a very serious safety issue that is under investigation. Would like to get reimbursed. Loss of brakes, unsafe to drive. Hissing sound from brakes when pressed

- Pomfret, CT, USA

Braking power booster system failed while driving. My booster brake and master cylinder went out suddenly and there were no warning lights. When applying full pressure on the brake, a loud hissing sound could be heard on the highway. In order to make a complete stop, I had to press the brakes far in advance of my stopping point to ensure the vehicle completely stopped in order to avoid hitting the vehicle in front of me. After this happened, I immediately drove the vehicle to my closest trusted mechanic (tires plus) to have the booster braking system inspected, and inevitably replaced. Tires plus completed the repairs and told me about another unrelated recall issue and recommended I take the vehicle to my closest Mazda dealership (classic Mazda orlando) to have the recall done for free. When I made the appointment for the unrelated recall item, classic Mazda informed me that the braking booster system that I just had replaced by tires plus was actually a warranty issue that Mazda corporate would have repaired at not cost. Classic Mazda suggested I file for reimbursement with Mazda corporate. Upon filing for reimbursement with Mazda, I waited about 4 weeks and then followed up with Mazda to confirm the date I should expect delivery of the check. At that time, they informed me that I was not entitled to full reimbursement because I should have taken or had the vehicle towed to my closest Mazda dealership for repairs. Not having any knowledge of the braking system warranty and fearing for my safety, I proceeded to have the repairs done immediately. All I want is for Mazda to fully reimburse me for the repairs and not just for "reasonable repair costs." This could have turned out much worse had I gotten into an accident, so shorting me $177 is a battle that I should not have to fight with Mazda corporate.

- Orlando, FL, USA

The brakes have become "hard" and have to be pressed all the way down to work. The car is slow to stop unless you jam on the brakes. It feels unsafe to drive as it appears a rear-end collision could easily happen. We have been told that the problem is the brake booster unit and there is an extended warranty to 7 yrs, 90K. However, this car has 91K.

- Katy, TX, USA

Vehicles brakes suddenly stopped working causing a low speed collision. I had the brakes inspected, and was told this was a known issue with my car, but Mazda did not initiate a recall. I then discovered that the NHTSA had struck a deal with Mazda, agreeing to an extended warranty with no customer notification. This is a clear case of a government Agency that is supposed to protect consumers, shirking their duty. NHTSA and Mazda you should be ashamed of yourselves!

- Lunenburg, MA, USA

Brakes make a hiss sound when pressed. Sounds like air leaking out. Very hard to brake. Sounds like brake booster as I read about this issue everywhere.

- Warwick, RI, USA

My brake booster has failed and caused a near crash. The hissing sound when pressing the break occurs and the brakes do not come to a complete stop. I had the vehicle inspected and the same brake booster failure that has been reported has been previously reported. I was never notified from Mazda of the warranty extension and now that my mileage is at 101,000 miles I've just missed the "warranty extension" and they refuse to make the repair. Why is this just an investigation and not a complete recall? Mazda clearly knows there's a problem and this can cause serious accidents with injury. My wife, who is the primary driver, is pregnant and have 3 small children that use this vehicle.

- Savannah, GA, USA

For several weeks now I have been hearing a hissing noise coming from my brake pedal when engaging the brakes. Now, for the past several days I have noticed that the brake deal become very hard to press down when trying to stop. Today I was very scared because I didn't think the car would stop.

- Newark, NJ, USA