2014, no-start issues

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by ascaloniannights, Apr 23, 2025.

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  1. ascaloniannights

    ascaloniannights New Member

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    Hi all, this is my first post here :)

    I have a 2014 that was passed down to me, 205k miles, all original except for a headgasket replacement a few years ago. I am a diesel mechanic, but new to hybrid and electrical tech so I'm learning as I go.

    On Friday, my car didn't start, dashboard lit up like a christmas tree, and stored some codes: P1390, P1391, P0A0F, C1259, C1310, and B1503. Cleaned the MAF and butterfly valve, found the 12V battery was around 10V, charged it overnight. Car ran fine for a couple hours before dying again. Put the 12V on a battery tester and it came up bad, so purchased a new one from the Toyota dealer. Once again, the car ran fine for a few hours, then died with the same codes, warning lamps, and hybrid system issue alarm.

    My question is, where should I start here? It seems like the 12V battery temporarily cures the issue, but its reading at ~13.5V while running, so I should think the car is charging it fine? I've seen talk of bad fuel pumps/filters, but the car running normally for a few hours seems to dispel that for me. Any thoughts?
     
    #1 ascaloniannights, Apr 23, 2025
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  2. bisco

    bisco cookie crumbler

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    maybe an intermittent fuel pump? but here's an interesting thread on the B1503, and a couple hours of heating up seems to match the code:b1503-code-under-uphill-load.207811
     
    #2 bisco, Apr 23, 2025
  3. ASRDogman

    ASRDogman Senior Member

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    You should fully charge the battery. At least 8 hours at 5amps or less with an AGM battery charger.
    Since it's new, that should fully charge it. Unless you drive for 3 or more hours, it won't charge it up.
    They don't charge the batteries, so they slowly discharge.
    That's the first place to start. If you haven't already, disconnect the 12v battery for 10 minutes or so.
    That should clear all the codes.
    If this doesn't resolve the issues, more trouble shooting is needed.

    What did you clean the MAF sensor with? You should only use MAF cleaner, not carb cleaner.
    Doing a duckduckgo search will reveal what the codes are.

     
    #3 ASRDogman, Apr 23, 2025
  4. ascaloniannights

    ascaloniannights New Member

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    could be intermittent, it just seems weird that it runs fine until stalling, and then just won't start at all after that. i would think you'd be able to refire it at some point if the pump is hit or miss

    thanks for the reply!
    both times, the battery was charged overnight on my AGM charger, and the issue was replicated. Additionally, both times I charged/replaced the battery, the battery was unplugged for an hour+. Warning lamps stayed off until the car stalled again.
    I know what all the codes are except for the C1310 and C1259, it looks like those are battery ECM specific codes. My scanner just gives me generics, so I dropped the car off with the dealer today so they can pull me some specific codes.
    As far as cleaning the MAF, I used MAF-specific spray. Probably CRC, I don't remember what brand I have
     
    #4 ascaloniannights, Apr 23, 2025
    Last edited by a moderator: Apr 23, 2025
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  5. MAX2

    MAX2 Senior Member

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    B1503 Exhaust Heat Management Warning Detected

    This DTC is stored when the combination meter assembly (No. 3 meter circuit plate) detects a malfunction in the water temperature sensor that is connected to the combination meter assembly (No. 3 meter circuit plate) via a direct line.

    When IG voltage is 9.5 V or more and the following conditions is detected:

    1. Coolant temperature sensor operation malfunction

    2. Coolant temperature sensor circuit open or short

    3. Engine coolant temperature is 120°C (248°F) or more


    Trouble Area:
    • Harness or connector

    • Water temperature sensor

    • Combination meter assembly (No. 3 meter circuit plate)
    Checking electrical connections


    Abnormal readings may be due to a break or short circuit in the electrical circuit.
    When everything is normal, but the sensor shows an excessive temperature, then it is necessary to look for the source of the sensor overheating.

    Tech Tips

    This DTC is for the water temperature sensor which is used to detect the engine water temperature sensor for the exhaust heat recirculation system, not for the engine coolant temperature sensor which is used for the EFI system.
     
    #5 MAX2, Apr 24, 2025 at 12:13 AM
    Last edited: Apr 24, 2025 at 12:23 AM
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