About this problem
The brake booster is the round canister behind the brake pedal that uses engine vacuum or an electric pump to multiply the force of your foot. Without it, the brakes still work, but the pedal goes hard and the car needs much more effort and distance to stop. Leaking boosters, failed check valves and worn vacuum pumps are the usual causes.
Across all owner complaints filed about the Mazda CX-9 since 2012, 96 (11.8%) describe brake booster failure and hissing pedal, the second most reported problem we track on the CX-9. The reports cluster on the 2012, 2013 and 2014 model years, and the 2012 drew the most, with 76. It tends to show up in the middle years of ownership: half of the owners who gave a mileage were between 40,000 and 84,000 miles. One report describes a crash or fire linked to it. No recall covers it, but Mazda has sent dealers service bulletins about it, listed below.
What owners report
Owners of 2010 to 2015 CX-9s report a hissing noise from the brake pedal and a hard pedal that takes more effort to stop. The cause is a failing brake booster. Mazda recalled some vehicles.
How it gets fixed
The fix is a new brake booster.
Typical cost: Free under recall if included; otherwise $600 to $1,000.
Complaints by model year
In owners' words
"We have noticed the difficulty in depressing the brake pad along with the hissing noise over the past 1 month and it has progressively became stronger. Initially you brush it off thinking you are imagining it."
2012 Mazda CX-9, 44,872 miles
"My 2013 Mazda CX-9 has 48,841 miles on it. Brakes recently started making a hissing noise then became hard to depress. I had a difficult time stopping the vehicle to avoid a collision on several occasions."
2013 Mazda CX-9, 48,841 miles
Excerpts from public owner complaints filed with the National Highway Traffic Safety Administration, lightly trimmed.
Service bulletins and warranty extensions
Mazda has sent dealers one bulletin that mention this problem on the CX-9. A bulletin tells technicians how to fix a known fault. It is not a recall, so the repair is usually free only while the car is under warranty or covered by an extension.
Mazda Motor Corporation is extending the warranty coverage for specific repairs for vacuum power brake booster units on 2007-2013 CX-9 vehicles produced from October 24, 2006 through April 26, 2013.
Before you buy a CX-9
- Press the brake with the engine running and listen for hissing.
- Test the brakes firmly at low speed.
- Check by VIN for open brake recalls.
Questions
Which Mazda CX-9 years have brake booster failure and hissing pedal?
Complaints are highest for the 2012, 2013, 2014 model years. The 2012 drew the most, with 76 reports.
At what mileage does it usually start?
Among owners who gave a mileage, the middle figure was about 58,000 miles, and half reported it between 40,000 and 84,000 miles.
How much does it cost to fix?
Free under recall if included; otherwise $600 to $1,000.