Master cylinder or brake booster failure on the 2011 Ford F-150
1 crash 1 of the 25 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 master cylinder or brake booster failure gets reported
Owners of the 2011 Ford F-150 report master cylinder or brake booster failure at a median of 50,000 miles. A quarter of the reports come in before 25,000 miles and a quarter after 80,000 miles, from 19 reports that carried an odometer reading.
A part like this is normally expected to survive 92,000 miles. It is the 21st most-reported problem on this model year.
The mileage distribution
The reported range runs from 20,000 miles at the tenth percentile to 110,000 miles at the ninetieth, a spread of 86,320 miles across the middle 80% of reports.
A spread this wide points at use rather than design. Towing, climate, service history and city mileage all move a failure like this, so the median is a weak guide to any individual car.
32% of the dated reports were filed under 36,000 miles.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| 21,280 miles | 26,723 miles | 52,300 miles | 80,000 miles | 107,600 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, 1 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 $450–$2,200 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 22 model years of this car. It shows up earliest on the 2005, at a median of 10,000 miles, and latest on the 1996 at 190,000 miles.
By volume the 2014 carries the most reports, with 110; the 2011 has 25. 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.
Truck is equipped with an eco-boost motor. Upon putting truck in reverse and backing down driveway, the brakes would not work to stop the vehicle. The pedal was hard to push and acted as if something was stuck under pedal. Driver went into neighbors yard and before striking the house, put the truck in park to stop. There was no objects behind pedal. After re-starting vehicle a few minutes later, brakes then worked as designed. The truck was brought to dealer were the ABS system was being looked at. After a week of miss-diagnosing, vehicle owner was told to pick up vehicle and experienced the same issue in the dealer parking lot and showed the mechanic and service writer and they concurred that there was a real safety problem. Upon leaving in rental car, vehicle owner witnessed a porter crash vehicle into a parked car. It was later determined that the brake booster assembly was faulty. *tr
Vacuum pump is defective and loses vacuum which causes brake booster to lose pressure and causes brakes to become defective upon start-up. Pump was replaced on 10/13, which corrected the issue for 4 months, pump was replaced again on 6/14 and is now failing and giving fault codes again (7/14). *tr
Service tech at dealership was test driving vehicle after a different repair. When he went to stop the brake pedal was hard as a rock and the truck would not stop. Found the vacuum brake booster went bad. This was three weeks ago and they still cannot get the part to fix it. As there are no repair parts in the system this must be a major problem with many vehicles. This is a safety issue which will get someone killed! My dealership said the truck is unsafe to drive. *tr
Also reported on the 2011 Ford F-150
Other powertrain problem
Other engine problem
Other steering problem
Other speed control problem
Other electrical problem
Other visibility problem
How far this goes
Complaints are voluntary, so 25 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 master cylinder or brake booster failure happen on the 2011 Ford F-150?
Across 19 owner reports that included an odometer reading, half were filed by 50,000 miles. A quarter were filed before 25,000 miles and a quarter after 80,000 miles. These are the mileages owners reported when they complained, not a prediction for any individual car.
How common is master cylinder or brake booster failure on the 2011 Ford F-150?
25 reports have been filed with NHTSA, about 0.1 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