2012 Mazda CX-9 service brakes problems

What owners report

• “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…”

  NHTSA complaint · filed 09/29/2023

• “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 f…”

  NHTSA complaint · filed 02/20/2023

• “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 …”

  NHTSA complaint · filed 08/18/2022

• “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…”

  NHTSA complaint · filed 03/28/2022

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

  NHTSA complaint · filed 01/09/2022 · crash

• “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.”

  NHTSA complaint · filed 10/05/2021

• “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.”

  NHTSA complaint · filed 10/04/2021

• “The contact owns a 2012 Mazda CX-9. The contact stated while driving 25 mph and approaching a stop sign, depressing the brake pedal the vehicle failed to stop. The contact stated that there was no warning light illuminated. The contact stated that she pumped the brake pedal and shifted to neutral until the vehicle came to a stop. The contact was able to drive to her residence. The contact took the vehicle to an independent mechanic and was informed that the power brake booster and master cylinde…”

  NHTSA complaint · filed 08/02/2021

Unverified owner reports from NHTSA's public complaint database.

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