Overheating light coming on temporarily then goes away

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by 805 Driver, Sep 3, 2021.

  1. 805 Driver

    805 Driver New Member

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    Hi everyone,
    I have a 2013 Prius 3 with almost 200k miles on it. Regular maintenance always performed and its run like a champ. I make the same commute M-F, approx 35 mins of hwy driving. About 6 months ago and 5 mins into my morning commute, the overheating light came on for about 5 seconds. I took it to my mechanic and could find no issue. Never had the issue again. All coolant levels were fine (no leaks) etc. Then last week, same thing happened at the exact same point in my morning commute. Literally came on at the same exact time (approx 5 mins) in my commute and lasted for 5 seconds then went away. Took back to mechanic, he performed a pressure test to see if there were any coolant leaks etc and again all was good. This morning again it happened at the exact same point in my commute. Exactly 5 mins in and lasted for 5-10 seconds then went away. After it goes away, it doesnt come back on for the remainder of the commute no matter how hard I drive it. In the afternoon on my way home (when the weather is warmer) I have not had this issue. Same with any other time outside of my early morning commute. Granted its only happened 3 times total but the fact that it has happened twice in the past week makes me want to be on top of it. I was running the heater the past two times this happened but didnt pay attention to hot air etc.

    Would this be a thermostat issue? Im at a loss as I have no fluid loss and again it only "overheats" very briefly at what seems like the time period when the car is reaching its normal running temperature after a cold night of sitting.

    Any thoughts?

    Thanks in advance.
     
  2. ChapmanF

    ChapmanF Senior Member

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    I would want to start by knowing what is overheating, as there is only the one warning light, but several reasons it can come on.

    If you have Techstream or something else that can datalog temperature readings, you might have it log the temperatures from the two engine temperature sensors (one of them shows on the Engine and ECT data list, and the other on the Combination Meter data list), and also some of the inverter and motor-generator temperatures.

    If the engine temperature shown on the Engine and ECT list goes too high, there might be a P0115 or P0117 code logged. If the engine temperature shown on the Combination Meter list goes too high, there will be a B1503 code logged. (it's possible some non-Techstream code readers won't show codes from the combination meter. If you are not sure about the reader you are using, you can use a resistor to spoof the temperature at that sensor and make sure your reader shows the B1503 code.)

    If the inverter, converter, or motor-generator temperatures are the ones out of bounds, there are several P0Axx, P0Bxx, or P0Cxx codes that might be logged. Again. not every code reader might be able to see those.

    Another quick thing to check would be to activate the engine water pump with the active test in Techstream and compare its reported RPM to the requested RPM shown, or also datalog the RPM of the pump during a drive. The water pumps in older Gen 3s can be dodgy.
     
  3. 805 Driver

    805 Driver New Member

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    I have none of this availability to me personally. Would it be best to take to the dealer? I have always had the worst experiences going to a dealer.
     
  4. Air_Boss

    Air_Boss Senior Member

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    If it is happening at the 'exact same location' (despite it being the same number of minutes into your commute, the amount of throttle application being variable nonetheless due to traffic conditions), I would suspect something eternal is triggering it, such as RF interference.

    I've had that happen in a Honda whose immobilization system light (but not the system, thankfully) was triggered at exactly the same location due to stray RF from a store security system.
     
  5. 805 Driver

    805 Driver New Member

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    Whoa I never thought of that. It is crazy because where it happens is right next to a power plant and under huge wires running over the highway. For those of you familiar with the area it is under the Morro Bay Powerplant lines.

    I will monitor.
     
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  6. rjparker

    rjparker Senior Member

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    I wonder if the radiator fan is initially slow to startup? Its a long shot.
     
  7. burrito

    burrito Member

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    If there are surface roads there, you could try pulling off and driving slowly under the power lines and see what happens.

    You might get cancer, but it's a risk I'm willing to take.
     
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  8. rjparker

    rjparker Senior Member

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    Pretty strange its his morning commute and has happened just three times in six months. And never on the return trip.
     
  9. Air_Boss

    Air_Boss Senior Member

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    Transients, like intermittents, are a b*tch to diagnose.
     
  10. sam spade 2

    sam spade 2 Senior Member

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    that was my thought.
    But the power line thing sounds like an even more interesting theory.
     
  11. 805 Driver

    805 Driver New Member

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    Ill keep you all posted. Any further thoughts or ideas would be greatly appreciated.
     
  12. rjparker

    rjparker Senior Member

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    The radiator fan came to mind since the last two overheats had the heater on and the first time six months ago was probably heating season as well. With cooling on, both radiator fans would be engaged from the beginning. A worn bearing, one fan failure or an out of range temperature sensor might delay or reduce the airflow once the engine warmed up completely.
     
    #12 rjparker, Sep 3, 2021
    Last edited: Sep 3, 2021
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  13. 805 Driver

    805 Driver New Member

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    Alright...just to follow up. The overheating warning light has been coming on more frequently but still not everyday. And to be clear, it is only coming on at the exact same spot in my MORNING commute. This morning I did not have my heater on and and it still came on in the same place in my commute. It is about 5 mins into my drive where I am assuming the car is reaching temperature, and then after about 10-15 seconds, goes away. It has only happened in the morning, I take the same route home each day (when it is warmer) and I have not had it happen one time.

    Any thoughts? I was intrigued by the RF interference theory (see above) as it does happen by the Morro Bay power plant lines each morning, BUT, it also doesnt happen on the way home and I drive the same route. Because it is a fair bit colder in the mornings and I'm driving a car that has been sitting for 15 hours, I am thinking it may be a bad radiator fan or even thermostat? I am going to take the car in to the mechanic next week but was curious if you all had any thoughts? If it were a bad radiator fan, would it only have the overheat issue once in the morning and then go away for the rest of the day?
     
  14. 805 Driver

    805 Driver New Member

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    And just to add some information to the above post...After the overheating light went off this morning...I drove the prius as hard as I possibly could (90 mph on the freeway, flooring it going uphill etc) on my commute and was unable to get the overheating light to come back on. It only happens briefly when the vehicle comes to temperature, then seemingly goes away. I am still worried that it will stay on one day and cause permanent damage. Again, coolant levels fine, no leaks etc.
     
  15. sam spade 2

    sam spade 2 Senior Member

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    Since you already have made the arrangements, take it in so they can check it.
    I suggest that you take a different route to work for a few days.
    One that completely bypasses the power sub-station or passes it 10-15 minutes later in the trip.

    In most situations, hybrid engines have difficulty getting and keeping enough heat, not over heating.
    If your heater is in use, I strongly suspect that the "radiator" fan wouldn't run at all with "normal" driving.

    I predict that the shop will say: " We don't see anything wrong." or "Can't duplicate the problem" and everyone knows that no amount of training and experience will allow a "mechanic" to have an idea of what to manually check when they can't make it fail. :whistle:
     
  16. rjparker

    rjparker Senior Member

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    First thing I would do is use a bluetooth obd2 scanner and an app to watch the temps. It should not be getting close to the warning temps. There are many who have had water pump intermittent failures where the impeller was dragging. I use an obd2 bluetooth scanner and an app called "Car Scanner". It has engine coolant temp, inverter temps, mig temps, battery temps, along with some so so pump and fan running data.

    http://bit.ly/ObdTwo

    A59BE6BF-8645-47F4-8319-F571CE2768AE.png
     

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    #16 rjparker, Sep 24, 2021
    Last edited: Sep 24, 2021
  17. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Maybe incidental but: have you cleaned the Exhaust Gas Recirculation circuit, including the Intake Manifold? If not, with 200K miles you're in prime head gasket failure territory. More info in my signature.

    Also, just editorial: is this a regular 3rd gen hatchback or Prius v. If the hatchback, maybe use the report button, on the initial post, and aske mod's to move. FWIW it probably doesn't matter much, Prius vs Prius v.

    For your overheat issue, and again with the 200K miles: I wouldn't hesitate, just change the water pump and thermostat. The pump's electrically driven (edited due to @ChapmanF points), with a plastic propeller, and the concensus here seems to be 150K miles is a good time to change both.

    Completely off-topic, but every time I read that it cracks me up.
     
    #17 Mendel Leisk, Sep 25, 2021
    Last edited: Sep 25, 2021
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  18. ChapmanF

    ChapmanF Senior Member

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    Electric water pump. Nothing electrical about the thermostat; it opens when some heated wax expands, same way it's been done since 1934.
     
  19. rjparker

    rjparker Senior Member

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    By the way, last night it was 73f ambient with the Prius cold. I hooked up Car Scanner for the pics above and drove it out of the neighborhood without using ac to a 60 mph highway to see how long it takes to kick on the radiator fan. Almost an hour later it was close to hot enough to kick on the fan as I ascended a 1/2 mile steep hill. So if the fan is sticking or only one of the two runs, it can be an extended time period.
     
    #19 rjparker, Sep 25, 2021
    Last edited: Sep 25, 2021
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  20. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Thanks for the editorial comment, fixed up.
     
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