Engine overheat & CEL P0117; no cabin heat

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by trvlmscl, Jan 15, 2019.

  1. trvlmscl

    trvlmscl New Member

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    Hey I've been a spectator on the site for a while, this is the first time I haven't been able to figure out my issue from searching other threads so I hope I can get some guidance.

    2010 Prius III, 132k

    Backstory: My dumba$$, probably. I recently replaced my headlights with LED and forgot to reattach the coolant hose to reservoir that I moved for clearance. I didn't notice any problems until scaling my way up to Sedona (1000ft > 4k) at 80mph. I obviously reattached the hose and topped of coolant at nearest gas station.

    Current symptoms: engine overheat light either is flashing or solid after a few minutes of driving. No cabin heat, even on HI (it's still chilly in AZ in Jan). The CEL comes on after a bit more driving. AutoZone scan returns P0117 - ECT sensor.

    Research: points to air in the coolant system, but all the threads relating to bleed are Gen II. I can't find any info/vids on bleed valves, etc for Gen III.

    Resolution: Thank you in advance for any advice, I truly appreciate it. I'm a student on a budget (45mpg helps!!) and hope that replacing a relatively cheap ECT sensor will solve my problems. I'm already motivated to do some serious maintenance, thanks to NutzAboutBolts on YT, but the coolant video did not address bleeding air from the system, which I suspect is a major factor in my situation. I hope I don't have to replace the water pump, but would much rather include it when I follow his other videos about spark plugs, EGR, and other cleaning/maint while I have full access to it.
     
  2. trvlmscl

    trvlmscl New Member

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    Can anyone give me a bit of guidance here - Gen III coolant bleed air? How can I tell if my water pump is failing?
     
  3. Raytheeagle

    Raytheeagle Senior Member

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    Gen3 doesn’t need to have an air bleed procedure. There is a high point bleed on the 2010 and 2011 but they removed it in 2012 as it isn’t required.

    It is very hard to tell if the water pump is failing unless you have a device to read temperatures like Techstream or an app for you phone.

    Mind sharing some more details?

    Good luck and keep us posted (y).
     
  4. Tim Powell

    Tim Powell Member

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    Did you ever find the problem? I'm having the same issue on a 2012 PriusV. Flashing or solid thermometer light and no cabin heat.
     
  5. trvlmscl

    trvlmscl New Member

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    As I mentioned in the OP I do indeed have a 2010 Prius Gen III, so what is this "high point bleed"?

    What other details can I provide? Especially with highway speeds the red temp warning light either flashes or is solid, and the check engine light comes on randomly also for P0117. The cabin heater also does not blow any hot air.
     
  6. Raytheeagle

    Raytheeagle Senior Member

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    Above the egr cooler there is a white valve stem on the 2010 and 2011 that can have a small tubing run added to the discharge of the valve that allows for aid on bleeding. Toyota did away with this ;).

    Some questions that will help us gain a better picture of your situation:
    • Miles on your Prius?
    • Any recent damage?
    • Is the car now losing coolant?
    • Do you have access to software like Techstream for diagnostic support?
    • You get the idea
    Good luck and keep us posted (y).
     
  7. ilovegirls

    ilovegirls Member

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    You should bleed the system. This is what happened to my old Honda and it fixed the problem.
     
  8. Raytheeagle

    Raytheeagle Senior Member

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    You ever try to access that bleed valve stem while the windshield wiper cowling is still on:whistle:?

    Let’s just say it’s a tight fit:cool:.

    I’ve changed coolant in about a dozen or so Prii and each time there isn’t air to bleed out;).

    That’s why toyota removed it in future model years(y).
     
  9. douglasjre

    douglasjre Active Member

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    A lot of people here are drawing rash conclusion s....is there antifreeze? Is the pump running? Have you done any diagnostics whatsoever?
     
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  10. Mendel Leisk

    Mendel Leisk Sand Pounder

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    If the bleed screw is missing (it's a black plastic connector with white screw cap, directly above EGR cooler), you could just pull off one of the topmost coolant lines there, and add coolant at the reservoir, until it starts coming out, then reconnect.

    Not sure if this would work, but worth a try I think.

    Squeeze/burp some of the hoses too.
     
  11. Mark Blazehak

    Mark Blazehak New Member

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    I’m having very similar problems to the OP; red Hi temp light comes on flashing? Then solid, sometimes goes off, sometimes stays on. If on for a long time (3-5 minutes), then check engine light comes on.
    So I hooked up a scan tool to OBD and monitored the ECT while driving. Generally goes up to 190-200 and hangs for a while, then starts climbing, falling,climbing, etc. sometimes getting up 20-40 degrees or more and then falls by 20-30 degrees. Eventually will get to 245 (flashing red light), then 250 (solid red light). I get the P0117 CEL at 275. Generally goes down when I slow or stop. I recently changed the radiator BEFORE all this because of a leak. Then changed the thermostat after it started this behavior. Worse since changing Thermostat. I lose a lot of coolant if I let it get past 250. I’ve stopped driving it until I can get it figured out.
    Have it scheduled for a coolant evacuate and flush at dealership.
    Ideas? Any advice will be appreciated.
     
  12. The Critic

    The Critic Resident Critic

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    Unfortunately, we have lots of wallet flushers and professional parts cannon operators in this section. ;)
     
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  13. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Someone with similar issues recently found it was air in the system, so maybe that dealership visit will resolve.
     
  14. Mark Blazehak

    Mark Blazehak New Member

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    Closing the loop; visit to dealership resulted in a diagnosis of a malfunctioning water pump. So I changed the water pump, which was surprisingly easy, and haven't had the problem since. Changing the water pump was much easier than changing the thermostat, although quite a bit more expensive. Car runs fine, just hope I haven't done any permanent damage to the engine from all the temperature fluctuations.
    I imagine the old pump was sporadically working just enough to cool the engine down at low speed.
     
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  15. douglasjre

    douglasjre Active Member

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    Thank you for closing the loop. I wish more people did this
     
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