For the past couple of months my 2019 MDX Hybrid is randomly doing a very weird noise that resembles a muffled air horn (think low volume 18 wheeler horn).
Everybody in the car can hear it so I know I am not losing my marbles…
The sound clearly comes from the outside and has no relation with engine/electric motor drive train or gears. I can hear it at low speeds in the city a few times per drive.
Any ideas?

 

I haven't heard any noise close that sound on my 19 MDX hybrid with +25,000 miles.

 

can you get the sound on video??

my first thought; it might be the horn...but without hearing it, who knows what it is.

 

Not knowing how loud the sound is or whether it's heard with the winows open or not - but there is a distrinctive audio sound the vehicle makes when in EV mode - which I think is required to alert pedestrians the car is coming. I know that when my wife drives up in her RLX Sport Hybrid that it's a very odd sound - sort of like a space ship sound from 50's Sci Fi movies :-) I've heard it somewhat from inside the car if the radio is off or when the windows are pen and you're driving under an overpass at low speeds. It's not loud, but it's there... But an audio of what you're hearing would help us diagnose more.

 

It would be darn hard to record it as I may be driving for an hour with nothing and then all of a sudden the sound makes it presence for 1 second.

 

I know exactly the sound you are describing (and I love it) but thats not the one.
The sound can be heard with the windows closed.

 

My 08 RDX had an issue with the A/C blend door that makes a moaning/groaning sound when adjusting behind the console. The fix was to lubricate the actuator arm; but, it would just return a few months later. Might be worth a try to see if hear the noise if the A/C is off or you manually set the controls to blow out of one set of vents only (no Auto climate control adjustments).

 

no one will be able to help you until you replicate the sound or take it in somewhere to get it properly diagnosed

 

does it sounds like someone let out a small fart lasting a second? It could be the A/C metering valve or compressor venting. My 2004 TL did this, once the A/C system was overhauled never heard it again. Not sure if the MDX Sport Hybrid uses A/C to cool hybrid batteries.

 

My RLX hybrid has a center mounted air grate above the 2nd row seat hump to draw in cabin air to cool the battery pack in the trunk. I don't remember seeing something that obvious for my MDX hybrid; but, I'm thinking it also uses cabin air to cool the battery pack. The hybrids have a second liquid cooling system just for the Power Control Unit or DC inverter (two radiator caps under the hood for hybrids). I "think" the PCU is located under the front center console in the spot a driveshaft would be on the sh-awd models if the sound is coming from that area.

 

Your description of the sound is not too far. It certainly sounds “airy” and lasts a second. Hence my original description as air horn.
The next time I take the car for service, I will have them check it out.

 

I was finally able to capture the noise using my iphone’s voice memo app. Hopefully this will help diagnose it, especially now that it is doing it more frequently.
I tried to upload it to this post but the file format is not supported. Any idea how I can convert it to one that it is compatible with this forum?

 

Sorry for resurrecting an old thread but i have this exact same sound from my '19 mdx hybrid. the intermittent muffled horn sound.
So i was wondering if it was ever determined what it was and if it was resolved?

Thanks for any help!

 

I took the car to the dealer twice, they heard the noise but have no clue what causes it.
I uploaded the file with the funky noise. Is that the sound your car makes?

 

yes, thats what i hear as well, just started a couple months ago. At first i thought someone was blowing their horn behind me.

i have no idea what it is. Strange. I assume its still occuring for you?
must not be anything to worry to much about if its been happening that long for you without any ill effects.
i am thinking its only something that happens on the hybrids or else others would have noticed as well.

 

I noticed it on my 2020 hybrid, especially during 20mph city turns, and once climbing a steep driveway, when my atf fluid was wearing out. With a 3x atf drain/fill (cheaper for hybrids since they use cheaper atf tham the zf9) the noise went away.

The noise started around 25k (after the car sat undriven for a month while I was on vaca) and I lived with it until my 40k atf MID drain/fill. Prior to the drain/fill the dealer couldn't reproduce and wouldnt diagnose unless they could reproduce. Happenned at least a couple times a week.

After the atf drain fill, it hasnt come back in 10k more miles.

 

Thanks for that info. I will mention it at my next service and see if that resolves it for me. My noise started around 21000 miles so quite similar to your experience.

 

Still doing the noise. In the span of 2 years I took it to 3 different Acura dealers. All were baffled and had no clue what caused it.

 

Maybe try replacing the ATF as suggested. My experience is similar to MVL as the noise started not long after my car sat unused for about a month ( actually a little longer )
I may just wait until that service is required since it does not seem to be affecting anything.

 

So this thread brought me back to an issue I had with my wife's '12 TL SH-AWD. I noticed a rumbling/gurgling sound that would periodically happen with her car. About the time it started, there was a TSB issued that described the sound, and the solution was to replace the in-line transmission fluid filter and do a drain-and-fill of the fluid. After that was done, the sound went away and never came back. Now I'm not sure whether (a) the 7-speed transmission of the hybrid has an external filter, or (b) whether this is even related. But given some earlier posts saying that a similar sound went away after a transmission fluid replacement, I'd be tempted to give it a try and see what happens. Could be the older fluid has different characteristics when going thru various passages, and creates some sort of sound or resonance. Strange.....

 

Yesterday the dealer said the ATF was fine and said they replaced the fuel filler neck because a technician noticed it was venting. No idea how he could have determined that because the noise is only done while in motion…

From the dealer home and on another short drive I did not hear the sound. Lets hope that fixed it.

 

Glad to report that since I picked up the car a couple of weeks ago, the weird noise is gone.
It seems that the replacement of the fuel filler neck did the trick.

 

I have the same noise. Vehicle schedule for service to fix a rattle and take a look at this noise.

Odd to me that fuel filter neck replacement fixed it. I get the noise seemingly randomly when accelerating thru about 1500 rpm. We'll see what they have to say.

 

I would also hear it at low RPM but I have the theory that it might also be doing it at higher RPMs but it was drowned by the engine/road noise.

 

Lalin,

Would you mind sharing the name of the dealer that did diagnosis and fuel filter neck replacement? I'm hoping Acura tech network has some info on this noise as it seems to be a prevalent problem. But, may ask them to contact dealership if they have no experience.

Thanks.

 

Acura of Ocean. 909 Route 35, Ocean NJ.
Alex was the service consultant. I am sure he will remember as I brought the car in multiple times for the issue (and other CarPlay related blues that are still unresolved)

 

Just following up: Has this noise come back? Or, do you think your fix was permanent. My car does this randomly. Not a huge annoyance but does happen.

 

so far, so good. The noise never came back.
lets hope it stays that way!

 

I've been searching for part called "fuel filter neck" and can't find it. The only thing that pop up is fuel FILLER neck.
Can you please point to the part number or some kind of a link? Thanks.

 

It may have been my typo.
I am currently out of town for the next couple of weeks. When I get home, I will look for the service receipt and let you know.

 

Take a look at the service order detail