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Ok here is a new one/thread i think? 17 EX 1500 miles, love to death. Scenario: haven't driven/started it in say 5 hours. I go out to get something out of it and i hear this constant buzz/drone outside car and underneath it would appear. (you can't hear from inside vehicle) i crawl under it record audio to play for honda dealer on Monday.. There is this constant buzz coming from area back around cat converter i think though its really hard to pinpoint exact spot as i hear it under front of vehicle i think....... Car is armed (alarm flashing) while all of this is going on..

I noticed the other night as well the same exact sound/scenario but didn't think anything of it....

Any ideas?
 

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Could that be the noise identified in another thread that is some type of fuel pressure test that runs intermittently after the car has been off for a while and is not an issue.
 

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Yes, probably the evap leak detection pump cycling.
^^^ This. It is normal. Ours does it too. I believe the test automatically runs based on change in atmospheric pressure, humidity or something like that. Read these...
http://www.crvownersclub.com/forums/137-2017-present-official-specs-features-etc-gen-5/137210-has-anyone-heard-sound.html

http://www.crvownersclub.com/forums/137-2017-present-official-specs-features-etc-gen-5/130649-noise-when-crv-turns-off.html
 

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Mine has the same noise. It is coming from the center of the vehicle and runs for 10-15mins maybe 3hours after engine shut off. It sounds like the fuel pump is running. The dealer says "I have no idea what that could be". I sent a video clip to them for evaluation - heard nothing back yet
 

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I hope this helps settle the concern with this noise. I've never heard it in mine simply because when I park my car, I only return to it 8-12 hours later so I miss the sound.

Text Font Line Document Number
 

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Since 1996 when OBD II became the law of the land we got reports of these strange noises long after the car was shut down. I always told people they were lucky to be close by when it happened as it was confirming the system was working as designed. The test that people are hearing is a required test for what is called a "Small leak test" of the fuel tank. This can set a P0442 or other code depending on vehicle. To run this test the car has to be stationary for a certain length of time with the engine off. This allows everything, especially the fuel in the gas tank to reach ambient temperature. Then, when conditions are met, the system will shut the purge valve and the vent valve to the charcoal canister. A small vacuum pump will turn on and draw a vacuum in the fuel tank. There is a pressure sensor in the tank and when the vacuum reaches a certain point the pump will shut down. The sensor then watches the decay rate of the vacuum and can determine if there is a small leak in the system. Loose gas caps were a scourge for this test and set many false codes. Some car makers even put a "loose gas cap" light on the dash as it was so common.

This is a EPA OBD 2 required test that all vehicles run. There are many variations in how car makers do this test, but they all have to run it. Even my Triumph motorcycle runs tests after its shut off. It make several weird sounds while doing so.
 

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We hear the same thing when we shut off our 2017 Honda CRV. Sounds like a buzzing noise coming from under rear end. We start the vehicle and it shuts off. We just started hearing this around 11,000 miles. We never noticed it before. Does anybody know what is causing the noise?
Should we be concerned?
 

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You will also hear a clicking noise when you open the driver side door...this is the electric brake boost system running a test before you drive away.
 

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We hear the same thing when we shut off our 2017 Honda CRV. Sounds like a buzzing noise coming from under rear end. We start the vehicle and it shuts off. We just started hearing this around 11,000 miles. We never noticed it before. Does anybody know what is causing the noise?
Should we be concerned?
Read my post #8 above. I taught this stuff for two different car manufactures since 1995. Or read this from another source:

https://www.newtis.info/tisv2/a/en/e46-m3-cab/repair-manuals/16-fuel-supply/2wiYkIx
 

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Thank you for this thread. I heard the buzzing sound on my 2018 Honda CR-V EX AWD when I went to the parking garage at work to take my afternoon nap. :sleep: It was 5 hours after engine had shut off. Thank goodness it was just the vaccum pump.
 
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