Loss of braking on the 2011 Mazda CX-9
2 crashes 2 of the 13 reports for this failure mention a crash, a fire, an injury or a death. Those are the owner's words on the complaint form, not a verified finding, and one report can mention more than one.
When loss of braking gets reported
Owners of the 2011 Mazda CX-9 report loss of braking at a median of 95,000 miles. A quarter of the reports come in before 50,000 miles and a quarter after 120,000 miles, from 12 reports that carried an odometer reading.
A part like this is normally expected to survive 78,000 miles. It is the 4th most-reported problem on this model year.
The mileage distribution
The reported range runs from 20,000 miles at the tenth percentile to 130,000 miles at the ninetieth, a spread of 112,001 miles across the middle 80% of reports.
When the reports scatter this far, the mileage is telling you about how these cars were driven more than about the part itself.
25% of the dated reports were filed under 36,000 miles.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| 17,570 miles | 49,828 miles | 95,100 miles | 121,427 miles | 129,571 miles |
Read the 10th percentile as “one report in ten arrived this early”. Exact figures are shown in this table because it is the table of record; everywhere else on the site they are rounded to the precision the sample can carry.
What a percentile can and cannot tell you here
These five numbers describe the readings owners gave, in order. The median is the middle one: half the reports arrived below it. The 10th and 90th are the edges of the bulk of the distribution, and the distance between them is the part worth reading. A tight spread — say 70,000 to 95,000 miles — points at something that wears out on a schedule, and the schedule is knowable. A wide one, 20,000 to 190,000, points at a fault that hits some cars and never troubles others, which means the mileage on the listing in front of you tells you very little about your odds.
What these figures are not is a survival curve. Every reading here comes from a car whose owner filed a complaint, so the sample contains only failures: it cannot say what share of the fleet made it past 150,000 miles untouched, because those owners had nothing to report. Nor is the mileage the moment of failure — it is the odometer reading as recalled at the time of filing, which may be weeks later and is sometimes rounded to the nearest ten thousand by the person typing it.
Percentiles are shown at all only once 8 readings exist for the vehicle and mode. Below that the middle of a handful of numbers is noise wearing a decimal point, so the figures are withheld rather than dressed up.
What happens, and what it costs
Of these reports, 2 a crash is mentioned. Owners write their own complaints and the agency does not verify them, so read this as what the reports say happened rather than as a confirmed count.
Putting it right typically runs $400–$3,000 at an independent US shop. That range is an editorial estimate held in this site's failure-mode catalogue, not a figure from NHTSA, and it is a repair cost rather than a diagnosis cost.
This mode is classified as critical, which means a failure can leave the car unable to stop, steer, or stay out of the way of traffic. It is weighted accordingly in the risk score.
The same failure on other years
The same failure is reported on 5 model years of this car. It shows up earliest on the 2010, at a median of 40,000 miles, and latest on the 2007 at 105,000 miles.
By volume the 2012 carries the most reports, with 18; the 2011 has 13. A mode that appears across most years of a model is usually a design choice rather than a bad batch.
If one year stands out to the left, that is the year to avoid; if the whole line sits at a similar mileage, this is wear rather than a defect in one production run.
Tick median reported mileage Solid middle half of reports Faint 10th to 90th percentile Colour how bad the failure is when it happens
What owners wrote
Verbatim from NHTSA complaint narratives, trimmed for length. The mileage is the one the owner gave.
Approaching a red light on a dry sunny day, my brakes failed halfway through coming to a stop. At first my vehicle (2011 mazda cx-9 sport with 56,000 miles) was slowing down normally and then suddenly there was grinding/crunching noises and despite pressing the brake, the vehicle was no longer stopping. I slammed the brakes, pumped a few times, and the vehicle simply failed to slow down or stop causing me to slam into the rear of the vehicle in front of me. I took the car into a mechanic who notified me that both of my "front calipers were possibly defective," and my front rotors were "uneven and wearing on the outside." however, my brake pads were good and did not need to be replaced. Good thing I was already stopping for the red light; therefore I estimate going about 10-15 MPH (speed limit on street was 35 and I was already midway through coming to a stop at the light). Imagine if I need to brake while going 60-70 MPH on the interstate! Or worse, driving in the rain! *tr
Brakes failed to engage 3 times this morning, the first time failed to stop the SUV so had to swerve to the center median and slightly hit the metal barrier. Then going back home making a turn, brakes failed again to engage. Seems this happened when making turns. Brought to the mazda dealer, told them about ongoing investigation by NHTSA about mazda cx9 2010-2011 brake problems. They did a thorough check but could not duplicate the problem so nothing was fixed. It might be the brake booster. I'm afraid this might happen again, they said there was no recall regarding brakes for 2011 mazda cx9. Hope that NHTSA forces mazda to make a recall. Mazda has to fix this dangerous problem. *tr
Without warning, the brakes failed. They seemed locked to the floor, impossible to press. No signal indicators no warning. Just suddenly no brakes. Very critical problem and accidents involving loss of life is probable. *tr
Also reported on the 2011 Mazda CX-9
Other brake problem
Master cylinder or brake booster failure
Differential or transfer case failure
Water pump failure
Airbag inflator rupture
Other powertrain problem
How far this goes
Complaints are voluntary, so 13 is a floor and not a count of affected cars. Mileages are typed in by owners and cluster on round numbers. And the mode itself is assigned by software reading the complaint text, which is reliable in bulk and fallible one report at a time.
Questions this page answers
At what mileage does loss of braking happen on the 2011 Mazda CX-9?
Across 12 owner reports that included an odometer reading, half were filed by 95,000 miles. A quarter were filed before 50,000 miles and a quarter after 120,000 miles. These are the mileages owners reported when they complained, not a prediction for any individual car.
How common is loss of braking on the 2011 Mazda CX-9?
13 reports have been filed with NHTSA, about 0.5 per 1,000 vehicles. Complaints are voluntary, so this is a floor rather than a count of affected cars.
What this is and is not. These are the mileages at which owners chose to complain to a federal agency, which is not the same as the mileage at which the part fails on every car. It skews toward failures that happened outside warranty, cost real money, or frightened someone. It is still the only public dataset that carries failure mileage at all, and the shape of a few hundred readings is informative even when a single one is not. Methodology · JSON · this failure on other cars
Source Owner complaints and recall records published by the US National Highway Traffic Safety Administration, model years 1996–2027 Figures rebuilt Published by AtWhatMileage How every figure is computed