C1391 ABS Code - How screwed am I?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by RSM151, Oct 28, 2025 at 6:17 PM.

Tags:
  1. RSM151

    RSM151 Junior Member

    Joined:
    Sep 26, 2023
    2
    0
    0
    Location:
    Florida
    Vehicle:
    2014 Prius
    Model:
    SE
    Unfortunately, yesterday the brakes on my 2014 Prius abruptly changed at the same time the ABS, Traction Control, and Parking Brake lights came on.

    Now that I am home, I hear the sound of a pump engaging for about 1 second every 4-5 seconds. Using techstream, I am able to see the C1391 trouble code.

    Given that the extended warranty period has ended (>10 years), I am somewhat terrified of what this bill is going to be.

    I am relatively handy and am willing to attempt a DIY (or at least some further diagnostic tests to localize the problem). Does anyone have suggestions regarding this? Given the frequency of the pump activating, I am going to try to listen for a leak as I have seen that mentioned previously. Any advice would be greatly appreciated; I'm a medical student and really, really do not have $3500 to spare if there is something I could do myself.
     
    #1 RSM151, Oct 28, 2025 at 6:17 PM
  2. Brian1954

    Brian1954 Senior Member

    Joined:
    Jan 31, 2021
    2,080
    808
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    You will need to use a mechanics stethoscope to listen for an internal leak in the brake actuator. You will probably not hear anything with just your ears.

    A DIY brake actuator replacement is not a very easy thing to do. The best thing is to try to find someone who has already done the job .
     
    #2 Brian1954, Oct 29, 2025 at 9:52 AM
  3. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
    3,361
    1,751
    0
    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    OK, so if you hear it leaking - then what?????
    A better path is to check your brake fluid level and make sure the issue isn't a burst brake line or caliper leak.
    If it is the booster/actuator assembly - you can replace it with a used one; but your gambling since that could be at it's end of life too.

    Good Luck......
     
    #3 BiomedO1, Oct 29, 2025 at 4:32 PM
(You must log in or sign up to post here.)