Loud fan noise when turning on

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Joe Dipierro, May 17, 2026 at 11:08 PM.

  1. Joe Dipierro

    Joe Dipierro Junior Member

    Joined:
    Apr 29, 2021
    37
    8
    0
    Location:
    SNJ
    Vehicle:
    2016 Prius
    Model:
    Three
    So a few months ago I noticed a loud noise when the engine would first kick on, maybe 3 different occasions. Didn’t think anything of it and then I heard it again the other day and today I heard it multiple times through the day. Mind you it was a hot day and I was in my car quite a bit today. I was parked and the engine goes off and comes back on and I hear the fan. It almost sounds like it’s gonna break but then it’s okay. Anyone know what this is or anyone else experiencing this issue? 2016 Prius here with over 242,000 miles on it now.
     
    #1 Joe Dipierro, May 17, 2026 at 11:08 PM
  2. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    10,707
    6,723
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    If you are parked using the ac the radiator fans are very likely coming on in high speed. Best thing to do is open the hood and observe.
     
    #2 rjparker, May 17, 2026 at 11:27 PM
  3. Joe Dipierro

    Joe Dipierro Junior Member

    Joined:
    Apr 29, 2021
    37
    8
    0
    Location:
    SNJ
    Vehicle:
    2016 Prius
    Model:
    Three
    Alright next time I have the chance I will, I’m not very mechanically inclined but I’ll try to see where the noise is coming from. Thank you
     
    #3 Joe Dipierro, May 17, 2026 at 11:35 PM
  4. Mendel Leisk

    Mendel Leisk MMX GEN III

    Joined:
    Oct 17, 2010
    61,185
    42,060
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    To clarify, this is the fans behind the radiator, in the engine bay? (My first thought was the cabin vent fan, and rodents...)
     
    #4 Mendel Leisk, May 18, 2026 at 12:22 PM
(You must log in or sign up to post here.)