1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Rookie: Narrowing down Code P2601

Discussion in 'Gen 2 Prius Main Forum' started by Ian Simons, Jul 12, 2021.

Tags:
  1. Ian Simons

    Ian Simons Junior Member

    Joined:
    Jul 19, 2016
    48
    3
    0
    Location:
    Lake arrowhead
    Vehicle:
    2007 Prius
    Model:
    N/A
    I just read my diagnostic report and code reader pulled P2601. I checked the coolant pump, and it’s still vibrating. Additionally the coolant is still simmering/bubbling. My question- a rookie question - I’m sorry: How do I narrow down the cause of code P2601?
    Or at least how do I narrow down what to say to the mechanic so they can’t make up stuff?

    I’ve never had a maintenance bill under $700.00, and it’s likely due to my ignorance, and I’m sick of it.
    Thx.
     
  2. SFO

    SFO Senior Member

    Joined:
    Feb 7, 2017
    5,286
    4,225
    0
    Location:
    Northern California
    Vehicle:
    2007 Prius
    Model:
    N/A
  3. Ian Simons

    Ian Simons Junior Member

    Joined:
    Jul 19, 2016
    48
    3
    0
    Location:
    Lake arrowhead
    Vehicle:
    2007 Prius
    Model:
    N/A
  4. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    6,085
    5,801
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    In the big picture, the CHS system merely keeps hot coolant available after the engine is shut down, so it can later send it back into the engine to help it warm up faster when you start it again. You basically have a large thermos in the driver side front fender with a pump that moved coolant between the thermos and engine.

    In the really big picture? It's an unnecessary system and would most likely make no difference in the drivability of your car. It will make a big difference in the hole in your wallet. My personal opinion? If the car is driving normally, as I expect it would, I wouldn't spend the money on the repair. Considering a recent post talked about an inverter cooling water pump replacement running about $700 (for what is really a 1 hour job), I couldn't image this repair being any less than that.

    And the pump you are referring to in your post is the inverter cooling water pump, which is not part of the cooling circuit referred to in the P2601. The P2601 refers to the engine coolant circuit, specifically the coolant heat storage tank and pump.
     
    #4 TMR-JWAP, Jul 12, 2021
    Last edited: Jul 12, 2021
  5. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    3,229
    1,348
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    So, a "Gen2" Prius (2004-2009) has FOUR coolant pumps. One electric pump is for the seperate inverter and transmission cooling system (the little coolant tank towards the back of the engine bay where the coolant "bubbles" or agitates when the car is in ready mode). The engine cooling system has 3 pumps; one mechanical unit driven by the belt off the crank pulley, one electric unit for the heater, and last electric unit is for the Coolant Heat Storage tank (US models only).

    The CHS is a thermos tank that keeps a few quarts of coolant hot (for up to 3 days or so) and then on cold startup pumps that hot coolant into the engine to reduce warmup times (and reduce tailpipe emissions). There is a temperature sensor for the CHS tank and one for the engine. If those temps don't change when the engine ecu commands the CHS pump on then it sets the P2601.

    I would think that a competent technician should be able to diagnose the problem within a couple hours, but he would need to be familiar with the Gen2 Prius and have an "advanced" scantool - such as Toyota Techstream or equivalent (Snapon or Autel). The actual repair cost would depend on what the fault is- cheapest would be a bad relay for the pump, replacing the pump (or getting into "complicated" wiring repairs) costs more.

    As TMR-JWAP stated, you will not notice any affect if this system does or doesn't function. Really the only reason to have it repaired is you want (or need) to have the check engine light off.
    Posted via the PriusChat mobile app.
     
    #5 mr_guy_mann, Jul 12, 2021
    Last edited: Jul 12, 2021
  6. Ian Simons

    Ian Simons Junior Member

    Joined:
    Jul 19, 2016
    48
    3
    0
    Location:
    Lake arrowhead
    Vehicle:
    2007 Prius
    Model:
    N/A
    Thanks Guys. To summarize the code is likely the result of a component from the chs pump or it’s wiring? I understand ignoring it would okay. However diagnosing it would be ideal, if not for anything else, but peace of mind. Agreed?
     
  7. cthindi

    cthindi Member

    Joined:
    May 8, 2009
    177
    85
    0
    Location:
    Connecticut
    Vehicle:
    2005 Prius
    Model:
    N/A
    I had a different code P1121 with CHS system. I could use the car for a long time without fixing it.

    What you may want to make sure is coolant level is correct and check it a bit more often.
     
  8. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,220
    15,048
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    As mr_guy_mann described, the P2601 code really only tells you about some observable situation (as is the case for any trouble code; what else could they be telling you about?). The code by itself can't tell you the cause of the situation.

    The "observable situation" leading to the P2601 is either: the system tried to pump hot coolant (above 65 ℃) from the thermos to preheat the engine, and didn't make at least a 2 ℃ difference; or, the system was tested by pumping a bit of the thermos-stored coolant five hours after the car was shut off, and didn't see the outlet temperature reading change by at least 1 ℃.

    So as you might guess, pump problems, valve problems, electrical problems, or sensor problems could all be possible reasons for seeing that observable situation. So the job of a person diagnosing a P2601 code will be to check through those possibilities until one turns out to be the cause. There are about six pages of suggested steps in the repair manual that can help with doing that.
     
  9. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    6,085
    5,801
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    If you're ok with spending $150-$200 for some one to look at it to tell you the problem is "X" and you trust them enough to believe them.
    Then what? You drive it as-is with $200 less in your pocket or they tell you they can replace X for $400 or so.. but then that doesn't fix it because they were wrong, but now need another $300 to replace X2.,

    Then again, it could be a $6 relay that ends up costing $306 to cover the diagnostic service, the $6 for a relay and $100 labor for the minimum 1/2 hour labor fee.

    sry, couldn't resist just havin fun :)
     
  10. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,220
    15,048
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    That's where the economic appeal of developing some, ahh, in-house diagnostic capacity starts to show itself.
     
  11. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    3,229
    1,348
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    If I had to pay myself for all the diagnostic and repair work that I have done on my own cars over the years, I would never be able to afford me.

    Posted via the PriusChat mobile app.
     
  12. Ian Simons

    Ian Simons Junior Member

    Joined:
    Jul 19, 2016
    48
    3
    0
    Location:
    Lake arrowhead
    Vehicle:
    2007 Prius
    Model:
    N/A
    You Guys know anyone in the riverside, Ca area that doesn’t answer to a boss about the day’s take who is a member on here. I rather pay an enthusiast, and not regret it either way.
     
    SFO likes this.
  13. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,669
    48,920
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    too far?
    /