2010 Prius with P261B water pump failure

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by decadude, Apr 30, 2022.

  1. decadude

    decadude New Member

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    2019 Prius
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    Limited
    I have a 2010 Prius with P261B water pump failure, but I am fearing that it could be a bigger problem I guess I will find out tomorrow as I hired a mobile mechanic to come look at the problem.

    The frustrating thing is to a lay person on cars I only saw hybrid system failure. This was the same thing I saw when I first got the car. So the car would die when this happened and I would turn it on and keep driving it as I had thought it was only hybrid system failure. There was no indication of overheating on the dash. The car would drive then the car would die. I was just trying to get home and then figure out what to do from there.

    Now the engine will not come on when I start the car. The ODBI code reader does only say P261B water pump on three different times for a 1 of 3 reading.

    Now since the engine wont start I am fearing bigger problems hopefully someone can chime in.
     
  2. AzusaPrius

    AzusaPrius Senior Member

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    IV
    Try resetting the code and then disconnect the power from the 12V for 5 minutes.

    Then reconnect the 12V and try and start the car.

    The system shuts the car down when the coolant gets hotter than 225F

    Damage will start to happen if it hotter than 214F for a long time.
     
  3. ChapmanF

    ChapmanF Senior Member

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    The original mistake was in assuming too much about what "hybrid system failure" means, and in assuming one "hybrid system failure" would be the same as an earlier "hybrid system failure", and in assuming it's reasonable to keep driving because there's "only" a hybrid system failure.

    The car's hybrid system consists of many important parts including the gasoline engine and the transmission—pretty much everything involved in making the car move—and has a couple hundred different ways it can fail (counting just the ways there are trouble codes for).

    When you get the warning triangle and the message, the thing to do next is to read the trouble codes so that you know what type of failure is being reported. Trying to assume or guess that information is a big gamble.

    There is an overheat light on the dash, but it seems to come on around 248 ℉, which you can think of as a usual threshold of "overheating" when otherwise the engine is working right.

    But an engine with a water pump malfunction is not working right. Its coolant isn't even circulating, so it has hotter spots and cooler spots and expansion stresses and the temperature sensors don't show what's going on except in the stagnant coolant right where the sensors are. So having a pump malfunction is a bigger problem than any ordinary "overheat", and that's why the ECM cuts the engine at 221 ℉ if there's a pump failure.
     
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  4. vss0253

    vss0253 New Member

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    Vehicle:
    2015 Prius v wagon
    Model:
    Three
    I have a 2015 Prius v3.I got a check engine light on few days ago. I went to advance auto to get it checked and it gave me a code p261b(1/3) stored. Engine Coolant Pump "B" control malfunction. After doing some search and watching YouTube videos I got to know it's Water Pump. So I ordered one. It took me 2 days to receive parts. Now my check engine light is gone and car runs fine. I have driven around 30 miles to check if light comes back on or it engine gets overheated. Nothing happened.
    From last 2 weeks I noticed that my car is not giving enough miles like it used to. I used to get around 49 miles/gallon and now its only around 35-36 miles/g. I do not know a lot about cars. I feel some fumes on my tongue since check engine light came on.
    I just want to know if I should go ahead and change water pump or wait till CE light comes on or there is something else wrong with it.

    Thanks
     
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