seeking assistance troubleshooting intermittent brake warning c1241, c1256

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by deadmandave, Jul 30, 2025 at 7:32 PM.

Tags:
  1. deadmandave

    deadmandave New Member

    Joined:
    Wednesday
    1
    0
    0
    Location:
    Portland or
    Vehicle:
    2009 Prius
    Model:
    N/A
    Greetings,

    My 2009 Prius has a very intermittent brake issue. maybe 3 times it has done the following:

    "Brake" light on dash illuminates, ! Abs shows up on the touchscreen and a loud alarm is sounding.

    This is resolved by a shutdown and restart. However one time there was no safe area to pullover and after a few minutes of driving with this alarm, brake power was reduced but not gone altogether.

    I took the car to a shop to run techstream and they found c1241 and c1256 and quoted 2600 to replace the brake actuator.

    The brake actuator acts normal at all other times imo. It runs for a few seconds on startup and when the brake pedal is depressed then it holds pressure and won't run again until a few minutes later. brake pressure is consistent and trouble codes/lights are not a common experience.

    I've checked what Ive thought of or what's easy,

    Brake juice is full
    Brake pedal switches are within spec
    12v battery is charged and healthy
    Engine ground is good

    This car has 130k miles. Had a new hybrid battery put in last year (maybe that's when the issue started?)

    Often the display screen is restarting (annoying yes. Related?)

    Possible water damage in the car? Slight rust/corrosion on some components in engine bay

    W hat else can I check before replacing the actuator, or should I just replace it? Abs module ground? Loose connections?

    Thanks Screenshot_20250730-163056.png
     

    Attached Files:

  2. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    12,322
    2,177
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    I'm going to have to guess a used actuator maybe? Because the 56 ending code is pressure in the system pump or accumulator..... Pressure issue .
     
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    26,697
    17,479
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    I would lean toward troubleshooting the C1241 first: inadequate electrical power getting to the brake components.

    Electrical power is needed to keep the pressure up, so having a second code about the pressure doesn't have to mean something else is wrong too.