Persistent High Frequency Whine in Cabin

[BeaverRat]

Hello,

I just bought a new 2026 Bronco Sport Badlands with the 2.0L - overall I'm really enjoying it, but there are a handful of small issues, the most annoying one being a persistent annoying tone audible in the cabin at all times. I've started digging into its origins, and I think I know where it is coming from. Here's some high level notes:

• The frequency of the tone is ~13.8 kHz. High pitched, but solidly within the spectrum my ears can easily here. About half the people I take in my vehicle can hear this frequency, mostly the ones below 35.
• The tone is not present when the car is "asleep", but as soon as I click the unlock button of the FOB, the engine bay makes a bunch of clicking noises as systems turn on, and when the various self checks complete, the high pitched tone is clearly audible, even over the headlight fans, and soft music playing in the cabin.
• From this point on, the annoying whine is present regardless of engine operation, and only goes away after parking the car, shutting off the engine, locking it, and waiting about 5 minutes for things to go back asleep.

There are several things I know that the noise is *not*

• It is not anything in the engine. The noise is present with the engine off.
• It is not the headlight fans, I unplugged those to rule them out, and make it easier to track down the source.
• It is not the center display, or the HUD display, and the tone does not change when brightness of either is adjusted.
• It is not the inverters for the 120V plugs.
• It is not the fuel pump.
• It is not coming from any of the speakers.

I took a few spectrum captures using a pretty slick website and my macbook pro: https://noisemeter.co/sound-spectrum-analyzer/ And while probing around, it became fairly clear that the noise was emanating from within the hood. I am pretty sure it is coming from the electric brake booster. This would make sense, as my friend's 2022 Bronco Sport 1.5L (which has the older style vacuum brake booster) does not make this annoying tone, it is totally silent in the cabin.

So my question to you all - Is anyone else experiencing this in their Bronco Sports? It is driving me nuts!

I'm worried that it is "normal" with this particular electric brake booster, as I found some videos of someone testing the Ford Maverick brake (which uses the same electric brake booster as this 2026 Bronco Sport Badlands), and I can hear the exact same 13.8 kHz noise in his videos! Is there anything I can do about this?

I attached a few spectrum plots, there's a ton of noise at 20 kHz when turning on the displays, luckily this is too high pitched for most adults to hear (including me), but the 13.8 kHz noise is an egregious oversight by Ford, as this is well within the range many adults can hear.

 

[Dude]

Wait you said under 35 and playing soft music?
Lol just kidding

Has to be something like a bad ground or bad component, gonna have to show all that info to the dealership and perhaps they can unplug more devices including that electronic brake booster to narrow down the source

Very unlikely (my opinion) Ford would release the 2026 design for production with a flaw like you described

Good work to rule out several of the most typical sources

 

[BeaverRat]

I tried to bring it to the dealership, but three (predictable) things happened:

1. They did not understand the audio frequency spectrum graph I showed them, pinpointing the problem frequency to 13.8 kHz
2. They could not hear the noise themselves due to their age
3. They thought I was crazy and hearing things

I also would be surprised if Ford released a design for production with this flaw, but I'm not sure how to proceed. If it is indeed a baked in issue with the electric brake booster, that seems to be a challenging issue to easily resolve.

I wonder if theres another owner of a 2025 or 2026 Bronco Sport Badlands that can corroborate my claims here. I think step 1 is to figure out if the problem is endemic in all of these newer Broncos with the new electronic brake booster, or if it's a one-off issue with my car.

 

[BeaverRat]

Ok, I'm getting quite sure now it's the particular electric brake booster making this high pitched noise.

Part Number: SZ1Z-2005-C

In these links, there's some videos of two separate guys complaining about a clicking noise in their braking. I don't have this particular clicking noise issue, but, even in their videos, the annoying 13.8 kHz tone is there! It's not what they're complaining about, but I can clearly hear it through my laptop speakers, and confirmed it's the exact same frequency with a handheld audio spectrograph.

https://www.mavericktruckclub.com/forum/threads/2025-maverick-brake-pedal-release-clicking-noise.61049/

https://www.mavericktruckclub.com/forum/threads/extremely-strange-brake-pedal-noise.46941/

Two separate people, with a different vehicle (but the same electric brake booster part number), with the same high frequency noise - it's got to be the EBB!

 

[Dude]

Try contacting your dealership or another Ford dealership to pull up all known issues with the EBB

it’s a shot in the dark but maybe if you go in early there would be a young tech or even a young salesperson you could get to sit in the vehicle .. anyone with good hearing

That might help your case

Otherwise you’ll need a set of good noise cancelling earpods, I have Apple AirPods Pro 2 which do a good job but that’s only a temporary possible solution if your state allows driving with earpods in

 

[Dude]

And there is this..

high-frequency noise or electronic whine from a Ford electric brake booster (EBB) common in modern F-150s, hybrids, and EVs is often the internal brushless motor and hydraulic pump building or maintaining pressure.

Quiet humming or buzzing during or right after pedal application is usually normal, but a loud, constant, or high-pitched squeal can indicate a failing unit or a pressure leak.

Normal Operation vs. Failure

Normal sounds: Brief electronic hum, soft whir, or click when you open the driver's door, press the brake pedal, or wake up the vehicle systems.

Abnormal sounds: Loud, high-frequency squealing, persistent whining that doesn't stop, or a buzzing noise that stays on continuously after the car is off.

 

[BeaverRat]

Maybe I’ll try a different dealership. Although I’m not hopeful that there is a fix due to being able to hear the same tone in the Maverick videos.

It may just be a poorly designed part. Likely scraped by their qualification due to being a sufficiently high frequency that most people cant hear, and *just* quiet enough that it is tolerable to most people.

I was trying to find out where you found that snippet on normal vs abnormal, is that AI generated haha?

 

[wireman]

Maybe go test drive another 2026 Badlands just to compare.

I have a 2025 BL but at 78 years old there are a lot of things I don't hear, per the wife.

Hope you get it figured out. You have done just about all the research and checking you can do.

Now it's up to Ford.

 

[DWG]

I have a 24 BS Badlands. I am one of those where the brake pedal started creaking when applying the brakes. The brake booster was replaced at 5000 miles. The brake power booster you are talking about is a different version only applicable to the Maverick from 11/24 to 3/25 and the BS after 2/3/2025. My brake power booster number is LX6Z2005AU. When Ford redesigns a part for what ever reason there are sometimes unintended issues that come up in the real world that Ford might either issues a TSB or SSM that fixes the issue or says it's normal telling the dealer do not repair/replace the item. You could be dealing with something like this where Ford will say it's normal and replacing the brake booster with a new one will still have the same noise you hear now.

I do not think what you are experience is normal even if only a percentage of the population can hear the annoying tone, Ford should hopefully find out what the issue is and change the brake booster design to eliminate the constant noise but I think that will take enough people to hear the noise and complain to Ford about it and if Ford does get enough complaints to look into the issue it could take a long time before they find or decide on a solution.


Here is the description of your Brake Booster. Note the start date of 2/3/2025.

• SZ1Z-2005-C
• :Booster Assembly, Brake Booster, Master Cylinder, Booster Assembly Brake
• Description:
  Maverick. From 11/24 to 03/25. Incl.ABS Control Module,Brake Master Cylinder,Reservoir. Bronco Sport. With electric booster. Exc.Vacuum Booster. From 02/03/2025.

 

[Dude]

Maybe I’ll try a different dealership. Although I’m not hopeful that there is a fix due to being able to hear the same tone in the Maverick videos.

It may just be a poorly designed part. Likely scraped by their qualification due to being a sufficiently high frequency that most people cant hear, and *just* quiet enough that it is tolerable to most people.

I was trying to find out where you found that snippet on normal vs abnormal, is that AI generated haha?

Just googled but I didn’t research beyond that

Dealership is going to be able to see in depth what’s been reported as issues

 

[supaDean]

I had a 2023 Bronco Sport Big Bend. During winter, the dashboard would creak something awful. It was loud and persistent and made driving the vehicle very unpleasant. Online forums also noted the problem. It was a major reason I ended up trading it in.

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