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Overheat Light after headgasket repair B1503

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Amarprius, May 23, 2023.

  1. Amarprius

    Amarprius Junior Member

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    Hey Guys Hopefully someone can give me some more tips or trouble shooting ideas, I bought a prius that had multiple misfires low coolant but no Overheat light on, Had my friend mechanic fix the headgasket clean out the EGR etc, he has done about 4 of these so far havent had this issue, when I picked up the car the coolant temperature light was on, Checked for codes, not much was found but B1503 Exhaust Heat Management Detected Talked to another expert said Waterpump, replaced waterpump with a Asin Waterpump, disconnected battery for 30 mins, the light immediately came back on and is steady not flashing.
    Any Ideas
     
    #1 Amarprius, May 23, 2023
  2. Amarprius

    Amarprius Junior Member

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    Some more info 2014 Toyota Prius I am leaning towards a temperature sensor? I dont think the overheat sign should come up on a cold start?
     
    #2 Amarprius, May 23, 2023
  3. JC91006

    JC91006 Senior Member

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    Did you polish the cylinder heads? Is the coolant full?
     
    #3 JC91006, May 23, 2023
  4. Amarprius

    Amarprius Junior Member

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    I dont think did not polish coolant is full I am leaning towards bad sensor,
     
    #4 Amarprius, May 23, 2023
  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    What’s the miles on it?

    How recently did you buy it?

    Did seller disclose the issues?

    Maybe he also dumped in a good amount of stop-leak product, clogged things up?
     
    #5 Mendel Leisk, May 23, 2023
  6. ChapmanF

    ChapmanF Senior Member

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    That code's for the separate temperature sensor for the exhaust heat recirculation system (EHRS). The names can be confusing, EHRS is separate from the exhaust gas recirculation (EGR) system. But the EHRS temperature sensor is the one at the top of the ∩-shaped hose at the back of the EGR cooler, just to make things even more confusing.

    Did that sensor get plugged back in? Did its wires get pinched somewhere?

    Toyota uses negative-temperature-coefficient (NTC) thermistors for those: as the temperature goes up, the resistance goes down. A disconnected sensor or open circuit will look crazy cold; a shorted circuit will look crazy hot.

    [​IMG]
     
    #6 ChapmanF, May 23, 2023
  7. Amarprius

    Amarprius Junior Member

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    Thank you to everyone, It was a simpler fix than anything, a connector was not pushed all the way in, I believe a ground. I really just got to say thank you to @Mendel Leisk for all the support he provides here and to the other members also, this place is full with too much info. You could literally rebuild the whole car with all the info here.
     
    #7 Amarprius, May 24, 2023
    Kromis and Mendel Leisk like this.
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