I was driving normally when I started sowing down and noticed the brakes were harder to push. I finally stopped just before almost rear-ending a vehicle in front of me. It turns out the brake booster, a known problem that was not communicated to me a few years ago, failed and makes braking the vehicle harder, increases distance, and makes the vehicle unsafe to drive. The problem has been reproduced via a diagnostic test at Mazda of Gladstone dealership on 9/27/23. The dealership has been the only people who have inspected the issue. There were no warning signs, no warning lights, nothing. It was scary because I didn't think my vehicle was going to stop. It's completely dangerous. I have not gotten the vehicle repaired yet because I believe Mazda holds responsibility as this has been a known issue with their cars.

- Portland, OR, USA

On August 14, 2020, the brake booster along with the master cylinder failed, resulting in very dangerous and frightening driving conditions, and the parts were replaced with Mazda original parts. This was an ongoing issue with the Mazda CX-9-??s. I reported it to the NHTSA, complaint number 11480067. On January 4, 2023, the brake master cylinder and booster failed again resulting again in very dangerous and frightening driving conditions. The car was driven only 25,383 miles before the brakes failed the second time. The Mazda parts were defective and continue to be so after many years with no effort by Mazda to improve these parts. Attached are the repair invoices for both incidents. I have tried contacting Mazda and they refuse to address the issue.

- Montville, NJ, USA

The brakes suddenly became very difficult to press as if I did not have power brakes. No warning lights came on and it became very difficult to stop the car. Then if I had to break suddenly and hard it would stall. I brought it to the repair shop and the brake booster was defective. The brake booster along with the master cylinder had to be replaced. It was a very dangerous and frightening experience the brakes suddenly difficult to use. I contacted Mazda customer service and they did not care. I then tried to escalate the issue over the last two years but it was impossible to contact anyone and all emails came back undeliverable. I just recently learned that I can report this danger to the NHTSA.

- Montville, NJ, USA

Brake power boost failure

- Raeford, NC, USA

This is relating to NHTSA Investigation PE 14-005. Although this car is a 2012 Mazda CX9, my wife driving the car had the same issue where she heard a hissing noise and the brakes were very difficult for her to depress or to stop. A brake issue is a major defect where the NHTSA should have initiated a recall in accordance with 49 U.S.C. 30118-30120, which required notification of all owners. Why the NHTSA allowed Mazda to only issue a 'Special Extended Warranty' is beyond me, and smells of a back door deal. Nonetheless, I was unaware of this issue with the Mazda CX9's as I was never notified. My wife drove the vehicle home and I purchased the replacement parts at my own expense. This should be a full recall and should be reopened as your current investigation PE 14-005 only included years 2010-2011, and did* include the 2012 model year.

- Waterford, VA, USA

I was driving along the highway and traffic began to slow. I pushed the brakes and the car did not stop.

- Kansas City, MO, USA

Brake booster failure caused a near miss. Wife driving with 5 year old daughter in the vehicle. The stopping force required on the brake pedal became excessive and the stopping (safe braking) distance significantly increased causing emotional distress. My understanding is this part (brake booster) has a defective diaphragm that deteriorates over time. The extended warranty created for this particular issue did not cover the vehicle at the time of the failure.

- East Brunswick, NJ, USA

BRAKE BOOSTER INTERNAL FAILURE - This is a known issue and a safety hazard on Mazda CX 9 models and should be investigated again regardless of the age of the vehicle.

- Livermore, CA, USA

The contact owns a 2012 Mazda Cx-9. the contact stated that while driving at approximately 20 mph, the brakes failed to operate. The contact mentioned that the brakes gradually slowed down the vehicle and stop independently. The vehicle was taken to an independent mechanic where they informed the contact that there was an unknown recall on the vehicle. The contact contacted riley Mazda (75 myrtle ave, stamford, ct 06902, (203) 978-5780) and was informed that the VIN was not under recall. The contact was informed of an extended warranty coverage however, the mileage had been exceeded. The manufacturer was notified of the failure. The approximate failure mileage was 129,000.

- Wilton, CT, USA

I was on the interstate (driving 60+mph) and the car in front of me slammed on their brakes for an unknown reason. I tried to use my brakes but they were rock hard and the pedal wouldn't depress. I was forced to swerve to the right, still having no brakes, and barely made it over 3 lanes to the shoulder of the road. In doing so, I caused total chaos around me, caused a tractor trailer to start to jackknife, which caused a chain reaction behind him. It was a total miracle that no accidents were caused and no one was killed. I called my mechanic from the side of the road, hysterical. He looked in his database and found that Mazda had known issues with their power brake booster. I subsequently found a letter from Mazda instructing owners "if your vehicle is functioning properly, there is no need to contact your dealer." Are you kidding me"??" my brakes were fine until they weren't, then I narrowly avoided being killed or causing the death of another because apparently Mazda's body count wasn't high enough to issue a recall.

- Atlanta, GA, USA

I was driving slowly about 30miph and began hearing a hissing noise when I depressed the brake pedal. Once I pulled into my driveway a small incline, and pushed the brake pedal it was very tight and stopped at a point, but would not go further, tried shifting different gears. Finally brake depressed. Hissing has continues, very stiff brake pedal

- Pflugerville, TX, USA

Brake booster on vehicle went out while driving, hard to engage brake and slow vehicle to a stop.

- Bethlehem, PA, USA

While pulling into my garage at low speed, my power brakes failed. I had to practically stand on the break pedal to get the vehicle to stop, barely stopping before hitting the fridge in my garage.the vehicle was towed for service and the problem diagnosed as the failure of the brake vacuum booster.

- Columbia, MO, USA

Brake pedal has become harder than usual to depress and the car does not start stopping until the brake pedal is depressed harder and further down. Also there is a hissing noise once the car stops and the brake pedal goes further to the floorboard. Once stopped and sitting the car will lurch as if it has been hit in the rear end. This all happens on any type of roadway. This has been going on for about two months and getting more pronounced.

- Louisville, KY, USA

When applying brake, hear hissing sound down at feet. Hard to stop, feels like pedal is pushing back. This happens at all speeds, even when putting car into gear from park. It has been ongoing for about 2 weeks. Mechanic advised it is the brake booster.

- Yardley, PA, USA

I was driving home with the family after viewing some house. Every time I would step on the brake pedal I would hear a hissing from the brake. Been happening for about a month now but, with the pandemic going on I just don't have time to diagnose the problem. When I press on the brake it would stop like normal with air hissing. The next day the brake pedal would feel very hard to press down. Like as if you been pumping your brake when the car off and when you turn your car on the pressure would be released. Not today, it stayed hard and hard to stop. I had to press the brake very hard as if pressing the brake pedal all the way down to the floor to make the car stop. Just stopping at a red light, stop sign, off the highway, and traffic was a challenge. I'll eventually stop but in the middle of a intersection or in the back of a car. If I had to brake because someone turned in front of me, I would of just hit them full speed because my brake booster failure to produce enough pressure to engage my brakes to stop. The day the brake booster happen to failure completely is when we had a family trip down to the Wisconsin dells over the July 4th weekend. Since brake booster wasn't a recall but an extended warranty and ended March 2015 or 90,000 miles. Mazada would charge me full price to get it fixed. I would not fell safe driving it to the dealer and mazada doesnt cover towing unless its within 3 years. So they'll tow anything in the 2017 and newer. 2012 mazada Cx-9 with 112,500. Owned it for exactly 3 to dated

- Maplewood, MN, USA

Purchased from a certified pre-owned Mazda dealer....I experienced, with no warning, my brakes become hard to press. It happens in reverse, coming off cruise, slow/fast speed, etc. I have to use an extraordinary amount of effort to press the brakes and bring the car to a stop. If someone pulls out in front of me, there is no guarantee I would be able to operate the brakes quickly enough to avoid an accident. I have children I Transport and it is concerning for me as a mom especially. A few times the pedal will 'release' and operate normally after the extra pressure is applied which causes the car to jerk to a stop because the brakes were being pressed very hard. Most times, extra pressure is required the entire time. This is a major safety concern and an issue I am aware is common in this model. Mazda extended this warranty to 90K and 7 years back in 2015; however, this does not cover used car purchasers. The issue was not disclosed to me in my purchase date of 12/12/2016. Had I known this major component could fail, I would have made a more educated decision on whether to purchase or request the faulty system be corrected.

- Lillington, NC, USA

I am now experiencing what Mazda mailed owners previously (see attached ssp93 owners notice) regarding "power brake unit warranty extension program ssp 93 2007-2013 Mazda Cx-9". I strongly believe that this is a safety issue since I find myself running stop signs when I try to stop the vehicle at an intersection. I know that Mazda extended the warranty to 7 years on it's ssp93 bulletin. But what happens to owners like myself who do not fall within that time-frame and are now experiencing this safety issue? it is unconscionable, that since Mazda has acknowledged this problem, that the owner like myself gets stuck with this safety problem concerning failure of the braking system on the Cx-9. please advise. Thanks.

- Pembroke Pines, FL, USA

As the car was being driven the breaks became hard and unless pressed very hard it keeps going. It doesn't go down at all. Assessment shows brake booster failure. It is weird other vehicle I had...a Toyota never failed. I can't drive it.

- Reseda, CA, USA

Brake booster failed. This is a known issue to Mazda. Mazda said to bring into dealer for assessment and consideration for goodwill warranty replacement. Dealer determined brake booster failed and Mazda then denied goodwill claim. I paid dealer to fix the issue. This is a major safety issue and should have been recalled, not granted an extended warranty.

- Largo, FL, USA