P1150 Code with no solution

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Kyra LeSene, Mar 12, 2026 at 7:44 PM.

  1. Kyra LeSene

    Kyra LeSene Junior Member

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    Hello All!
    I have an 06 prius, she had an overheating issue that turned out to be a blown head gasket so I swapped the engine. She no longer overheats but is still giving the code P1150, I have changed every pump and bled the system and nothing will take the code away. I scan the car using an Innova 3100 code reader. This issue is making it impossible to smog. The cat and 02 sensors were replaced a year or two ago. Each time I scan the car with the check engine light the I/M Monitor status on the "cat" and "o2s" are both either red or green (the "eva" remains red). But no other code pops up. I am at a loss and don't know what to do anymore. I have search on Google and other threads. If someone has any insight and can assist I would be most grateful thank you.

    P.S To clear up any confusion the image says P1150 (1 of 2). But are duplicate codes. One is "Toyota Stored" the other is "Toyota Pending".
     

    Attached Files:

    #1 Kyra LeSene, Mar 12, 2026 at 7:44 PM
  2. ChapmanF

    ChapmanF Senior Member

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    First use Revelio to find where the clog is, then use Reducto to clear it.

    Be careful with the Reducto that you don't blast the thermos, pump, or valve to bits.
     
    #2 ChapmanF, Mar 12, 2026 at 8:27 PM
  3. dolj

    dolj Senior Member

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    This code is well covered in many threads here in the Gen 2 forums. Just use DuckDuckGo/Google to search this site for P1150:
    Code:
    site:https://priuschat.com/ Gen 2 P1150
    The repair manual is the best place to learn about this Toyota Prius specific code. Your search (as above) should give you many hits that include an attached excerpt from the Repair Manual that covers this specific code.

    The clog or blockage is one conclusion that Toyota thinks is highly likely, but the actual conditions that cause this code to set is about the temperature sensed coming out of the coolant heat storage system (CHRS) tank.

    Specifically P1150 sets when the following conditions are met:
    • Change in CHS tank outlet temperature and engine coolant temperature after the water pump is turned ON during preheat mode: less than 2°C (3.6°F)
    • Change in CHS tank outlet temperature when the water valve is opened to the tank, with the engine warm: less than 3°C (5.4°F)
    The suspected causes, in order, are:
    • CHS tank outlet temperature sensor
    • Water valve (coolant flow control valve)
    • Cooling system (clogging)
    • ECM
    You can read the full information in the Repair manual.

    I hope that helps.
     
    #3 dolj, Mar 12, 2026 at 10:08 PM
    Last edited: Mar 12, 2026 at 10:18 PM
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