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Engine always running

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by flamebird, Jan 17, 2013.

  1. flamebird

    flamebird Junior Member

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    Hi everyone,

    I have a Prius C with 10,000km / 6,200mi. It recently developed an intermittent issue where the petrol (gas) engine does not shut down at times when the car would normally be in EV mode (downhill coasting, stationary, etc). This does not happen every time, but only on around 50% of trips.

    Once the problem occurs, it will continue until the car is completely switched off, regardless of how long the trip is. If I restart the vehicle, the issue will sometimes disappear. I have been in the car driving normally for well over an hour, and the engine has not turned off the whole time. As a result, fuel economy is suffering.

    As it's still under warranty, I will be taking it to the Toyota dealer. However I thought I'd see if anyone else had seen this issue, or if anyone knows what the cause might be. Thanks!
     
  2. cwerdna

    cwerdna Senior Member

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    Is the heater on? See Why mileage gets worse in winter | PriusChat, under the better heater management section. Yeah yeah, I realize it's summer over there.

    On the Gen 2 Prius, at above ~42 mph, the gas engine must run. I believe on yours, the threshold might be 46 mph. There are others reasons for it to run, such as low HV battery charge and to warm up the catalytic converter (if the engine's cold).
     
  3. flamebird

    flamebird Junior Member

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    Hi cwerdna,

    The heater is off - when the problem occurs, the engine will run whether the heater or A/C is on or off. This definitely isn't the normal behaviour you describe - as you said, the engine will run to charge the HV batter or warm the catalytic converter. However when this problem happens (not every time, but around 50% of the time I drive), the engine will run 100% of the time, no matter what the state of the battery is. I can come to a complete stop, with the battery showing full charge, and the engine will run indefinitely.

    Dearler update: No error codes have been recorded and the dealer tried to say there was no issue, and it was just normal operation. I explained that I am aware of what the normal behaviour is, but that on some trips, the engine will just run 100% of the time and never shut off (until the car is powered off).
     
  4. F8L

    F8L Protecting Habitat & AG Lands

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    Could the 12v battery be shorting or something else that is causing a large continuous power draw?
     
  5. flamebird

    flamebird Junior Member

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    It's possible - is there any way to tell if this is the case? The problem comes and goes, unfortunately, so it's difficult to do testing/diagnosis.
     
  6. F8L

    F8L Protecting Habitat & AG Lands

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    You can try a simple check of the 12v battery voltage with a volt meter. Make sure the car has been sitting off for at least 6hrs.

    You can have the battery tested by the dealer or independent auto parts store.

    It's worth a shot before you go after the dealer. :)
     
  7. flamebird

    flamebird Junior Member

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    Thanks F8L, I'll get this tested!
     
  8. CMJAnew

    CMJAnew Junior Member

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    Being mechanically challenged, I would ask you to explain the relationship between the 12v battery voltage and the ICE not shutting down. Thanks
     
  9. flamebird

    flamebird Junior Member

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    Frustratingly, the dealer tried to give me a lecture on how a Prius works because they could not replicate the issue. I explained to them that it's not normal for the vehicle's engine to run non-stop for an entire trip lasting over an hour. However I do understand that since they couldn't observe the problem, they couldn't do much.

    There doesn't appear to be any voltage problems causing a high draw, and there are no error codes recorded.

    The issue hasn't happened again since last week, so all I can do is wait. For now, it remains a mystery.
     
  10. JMD

    JMD 2012 Prius 4 Solar Roof

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    Are you driving many short trips? The Ice needs to run to warm the converter up. What is the MPG you are getting?
     
  11. F8L

    F8L Protecting Habitat & AG Lands

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    Were you making a lot of very short trips prior to the incident? Maybe the hour long trip charged the battery back up?
     
  12. flamebird

    flamebird Junior Member

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    Hi JMD - I'm familiar with the time required to warm the catalytic converter, this incident has occurred multiple times on several long journeys. At other times, the car operates normally.
    Hi F8L - It happened several times over the last 2 weeks, after both long and short trips. For example, I took a long (45 minutes) drive, the ICE was running 100% of the time. After restarting the car, the problem continued. It seemed to happen regardless of HV and 12v battery charge.
     
  13. F8L

    F8L Protecting Habitat & AG Lands

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    Ok. Well that would rule that out then.

    Does anyone remember what the ECU problem was on the earliest c? I seem to remember someone having an issue with poor fuel economy and I thought it was similar to this.
     
  14. JMD

    JMD 2012 Prius 4 Solar Roof

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    Perhaps the computer that controls the Ice and battery management is malfunctioning. Try a different dealer. What is the MPG? Is it off plenty? That may be where the conversation starts.
     
  15. ufourya

    ufourya We the People

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    There is something I haven't seen mentioned here. Is there any possibility that you are travelling with anything in the rear footwell that might block the air intake that keeps the main battery from overheating? I understand when this happens the battery ceases to operate normally and ICE runs full tine.
     
  16. Gcoop

    Gcoop Member

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    i was going to say the same thing as above
    i remember another poster here having a problem where the engine wouldnt go into ev
    problem was there was something in front of the vent in the back seat
     
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  17. dick_larimore

    dick_larimore Member

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    While on the idea of a hot (temperature) high voltage battery, possibly the cooling fan under the back seat does not operate.
     
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  18. flamebird

    flamebird Junior Member

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    It looks like you folks may have been on to something! I located a plastic shopping bag that was firmly lodged against the vent, partially blocking it. Thank you all for suggesting this! I had no idea the vent was there.

    I'll see if the problem goes away and report back.
     
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  19. ufourya

    ufourya We the People

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    You're welcome! I'm betting everything will get back to normal.
     
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  20. flamebird

    flamebird Junior Member

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    Just a quick update - the car has behaved normally since I removed the blockage. We are expecting some hot weather this week, so it will be a good test. I'm confident the problem is solved, thank you all again.

    On a related note, it's disappointing the dealer didn't think to check the HV battery ventilation after I reported this issue!
     
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