Humming/Buzzing Engine Compartment?

2021 HONDA ACCORD
48,000 MILES • 2.0L • 4 CYL • 2WD • AUTOMATIC
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WUMBO75
  • MEMBER
  • 1 POST
I am getting a strange buzzing/whining/humming noise coming from the engine compartment on a cold startup. It’s honestly hard to describe the noise, it almost sounds like the noise a Cicada makes. It will make the noise for a while and then eventually stop if it is left idling. But it completely goes away once I put the car in gear (this includes reverse and drive). I am mechanically inclined, but this one has me stumped. Any ideas?
Jul 22, 2025 at 2:02 AM
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CANNON1349
  • ✓Experienced Mechanic
  • 861 POSTS
Hello, is it possible to upload a video of the sound? I have seen many things buzz at idle, like belt tensioners, pulleys, compressors, etc. Also, automatic transmission valve bodies may buzz until put in gear, or vice versa. These newer Hondas also have an integrated PCV valve in the valve cover that can whistle or make weird noises when failing. If you can help pinpoint the location, we can assist you better.

Thanks,
William
Jul 22, 2025 at 12:28 PM
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