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2010 Prius, P261B error

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by MikeB6, Oct 19, 2018.

  1. MikeB6

    MikeB6 Junior Member

    Joined:
    Apr 21, 2015
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    Dallas
    Vehicle:
    2008 Prius
    Model:
    ----USA----
    2010 Prius stalled few times with check hybrid error. Techstream identified error code P261b. Pulled and tested the water pump, it's turning fine with no resistance, also changed the coolant. The odd thing, this behavior only occurs when the outside temperature is below 60F. When the temperature is above that, even in 90s, I never get the error. Several posts refer to P261b as a pump related issue, is there anything else I need to check beside the pump?
    Error Code: P261B: Engine Coolant Pump "B" control Malfunction.
     
  2. davecook89t

    davecook89t Senior Member

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    Vehicle:
    2017 Prius
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    Four Touring
    Based on the description of your car reporting this error only at certain temperatures, it would be fair to ask whether the sensor producing the code is really the component that is at fault, rather the mechanical parts of the pump. Reading through this thread, https://priuschat.com/threads/check-hybrid-system-with-code-p261b.177726, it appears that this code can appear intermittently with no apparent loss of function by the pump, which would lead one to further question the reliability of the sensor. In any event, it appears that the sensor is built into the pump so that part cannot be replaced separately. Rather than assume that the sensor is at fault, and take the chance that the pump will continue to function normally, it looks like most people have chosen to proactively replace the pump. I suppose what you choose to do will depend on how confident you are in your ability to recognize when the pump has actually failed and how quickly you can react to replace it.
     
  3. MikeB6

    MikeB6 Junior Member

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    Vehicle:
    2008 Prius
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    ----USA----
    davecook89t,

    Your feedback makes a lot of sense. I will change the water pump soon. Thank you for the recommendation.
     
  4. Michael chong

    Michael chong New Member

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    Aug 28, 2019
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    Location:
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    Other Hybrid
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    Hi new here, driving a 2014 Fieder spacewagon hybrid in Singapore and yesterday morning engine check light when started the car. Vehicle behave normally but worried so went for a diagnostic check and this P261B came on current. So reading you guys previous comment recommended the engine coolant pump replacement. Hope to get more details about this error code. Thanks !!