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P148F and P261B codes but engine coolant temperature remained under 90°C

Discussion in 'Prius v Technical Discussion' started by Ohid, May 14, 2022.

  1. Ohid

    Ohid Member

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    Gave P148F and P261B codes but coolant temperature rarely crossed 90°C. Mostly remain under 90°C at Highway driving. Speed also not crossed 95 km/h. Should I go for water pump replacement?



    Prius v 2015
    Odo 99k km.
     

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    #1 Ohid, May 14, 2022
    Last edited: May 14, 2022
  2. ChapmanF

    ChapmanF Senior Member

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    The problem isn't necessarily the pump itself, but troubleshooting should be done to find the cause, and whatever the cause, it should be corrected.

    If you have a scan tool that can retrieve freeze-frame data, you can look for freeze-frames with those codes and check what the pump RPM was.

    If the pump doesn't turn, the temperature sensor only knows the temperature of the coolant it's sitting in.
     
    #2 ChapmanF, May 14, 2022
  3. Ohid

    Ohid Member

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    I have BAFX scan tools which not provide water pump rpm. I did Intake manifold and EGR pipe cleaning 2 weeks ago. When I reassembled and started engine, first was loud rattling and shaking. After 1/2 minutes, rattling and shaking disappeared. I scanned it and got P148F code on Car Scanner software but on Torque pro no code showed. I erased the code. After 912 km, the code come again alongwith P261B code.

    In some priuschat thread discussed the air trapped in the coolant causes P148F code. I didn’t remove coolant line from throttle body during intake manifold cleaning. So I am confused, it is troubling from Water pump or Air trapped in the coolant. Since coolant temperature not crossed 90°C, the confusion aggravated more. Please suggest.
     
    #3 Ohid, May 14, 2022
  4. Ohid

    Ohid Member

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    Screen shot of freeze frame data. All are within range. Pump rpm not available on my scanner
     

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    #4 Ohid, May 15, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    The electrical connector for the water pump is a likely one to be disconnected during manifold/EGR work. Are you completely convinced it was reconnected well and in good condition?

    Inconvenient that the scan tool doesn't show the target and actual pump speeds. You can review this thread over here for the electrical details of how the target speed is sent to the pump (on the WPO wire) and the actual speed is sent back (on WPI) if you need to snoop on them yourself.
     
    #5 ChapmanF, May 15, 2022
  6. Ohid

    Ohid Member

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    I didn’t disconnect water pump switch during intake manifold cleaning. Today car was overheating and stalled on the road. Come to home with three intervals to cool down engine. I bought new water pump and hopefully install soon.
     
    #6 Ohid, May 15, 2022
  7. ChapmanF

    ChapmanF Senior Member

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    I hope the pump turns out to be the problem (or they'll accept a return if it isn't).
     
    #7 ChapmanF, May 15, 2022
  8. Ohid

    Ohid Member

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    Old pump rotor has cracked on its edge, picture attached . I installed new pump and so far so good. After erasing code, no check light and code. Thanks for your input.
     

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    #8 Ohid, May 16, 2022
  9. ChapmanF

    ChapmanF Senior Member

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    (y)
     
    #9 ChapmanF, May 16, 2022
    Ohid likes this.
  10. Ohid

    Ohid Member

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    during my Water pump change I didn’t air bleed on maintenance mode. I did it with reserver cap off in engine running in ready mode for more than 20 minutes. I am little confused whether all the air bubbles were removed or not. Though car still run fine and temperatures rarely crossed 90°C. Also I didn’t try it on the highway with constant speed above 90 km/h.

    Should I go for air bleeding with maintenance mode? If so, do I need to drain coolant again and refill again?

    Thanks
     
    #10 Ohid, May 20, 2022
  11. ChapmanF

    ChapmanF Senior Member

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    It seems to me that people make a much bigger deal of burping the cooling system than is really warranted. It might be blending in people's minds with what they know about brake bleeding (where small bubbles can get stuck indefinitely and interfere with braking) or human circulation (where a bubble in the bloodstream can stop circulation because the heart pumps by pulsing).

    The engine's water pump doesn't pump by pulsing, it moves a steady stream of water that can carry bubbles through the system, and the hoses shown in blue here collect any bubbles constantly from high points in the system and deliver them to the top of the degas bottle where they belong. That's, in fact, what does most of the work for you after your initial fill, when you run the engine up to operating temp and let it run several minutes.

    As long as you had the bottle filled to B when you started, and the level dropped all the way to F after cooling when you were done, you're good.

    If it ended up still a little above F, you might just repeat the warm-up process. No need to drain and refill. Do put the cap on this time, though. That's how the manual says to do it. That way, the system can build pressure, making the bubbles smaller and more mobile.

    [​IMG]
     
    #11 ChapmanF, May 20, 2022
  12. Ohid

    Ohid Member

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    Thanks for clarification. Actually, first I did fill initially higher than F line may be near B line, then start engine and run more than 10 minutes. Coolant dropped below low line and again filled it near B line. Again engine run for few minutes upto 2500 rpm. This time coolant dropped very little and it was 1/2" higher than F line. Next day after running nearly 20 kms it was remain same. So I pulled the excess coolant from the tank using syringe. Still it just above the F line after 6 days.
     
    #12 Ohid, May 20, 2022
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