2017 Prius Check Engine Light

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Muhammadk, Feb 2, 2026 at 9:08 AM.

  1. Muhammadk

    Muhammadk New Member

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    Location:
    Ontario, Canada
    Vehicle:
    2017 Prius
    Model:
    Four
    I have an idea of what the issue is but I just want to confirm before I go pointing fingers at people in my household.

    My check engine light is on and, when my mechanic checked, he said it had something to do with temperature. What I believe is happening is that something happens with the thermostat or something related to it when the engine isn't allowed to get up to temperature before driving. The issue only comes up when I don't let the engine pre-heat for at least 10 minutes.

    The mechanic cleared the code and I hadn't had an issue, even after driving 40 minutes straight. The light didn't come back on until my sister used my car recently and, while I mentioned to her that she needed to warm up the engine before driving, I don't believe that she did, hence the engine light coming back on.
     
    #1 Muhammadk, Feb 2, 2026 at 9:08 AM
  2. Brian1954

    Brian1954 Senior Member

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    Jan 31, 2021
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    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    What was the actual trouble codes that the mechanic found. Without the trouble codes, everyone reading this thread can only guess what the problem is. The probability of guessing correctly is very low.
     
    #2 Brian1954, Feb 2, 2026 at 8:12 PM
    BiomedO1 likes this.
  3. BiomedO1

    BiomedO1 Senior Member

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    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    Need error code(s).......
    Modern ECU, fuel injected cars DO NOT need warm-up before taking-off. You should take it "easy" on the engine until it warms up, but does not require 10 minute warm-up. If your battery level (SOC) is high, putting the car into Ready mode won't even fire the engine anyways - so how is it warming-up?????o_O:(:whistle:
    The 2016-2018 Prius are prone to exhaust gas heat exchanger leaks. If your coolant level is low that can cause temperature issues, but I'm just guessing without the error codes.
    Something is off or your misunderstanding the mechanic or the mechanic doesn't know what they are doing. As I stated in the previous paragraph, putting the car into ready mode doesn't guarantee an engine start.
     
    #3 BiomedO1, Feb 2, 2026 at 10:00 PM
    Last edited: Feb 2, 2026 at 10:36 PM
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