Break down today. Pulled codes. Need feedback on it.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by TechBill, Mar 4, 2026 at 1:04 PM.

  1. TechBill

    TechBill New Member

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    I had a breakdown today with my 2007 Prius and got the red triangle and the car icon with the exclamation mark on the MFD. The car shut down and I had to pull over.

    I pulled the codes with Dr Prius and this is what I got.

    P3190
    P0171
    P0420
    P0A0F

    The P3190 is confirmed and the others showed as pending earlier. The Dr Prius full battery test also showed P0A0F which says engine failed to start.

    From what I can see the hybrid battery seems balanced. Voltage difference around 0.04 to 0.13 and internal resistance around 21 to 23 mΩ. Temperatures around 90 to 100°F.

    Here are the numbers I saw during the battery monitor.

    Pack voltage about 205 to 232 V
    State of charge about 48 to 58 percent
    Block voltages mostly around 14.5 to 14.8 V
    Volt diff about 0.04 to 0.13 V
    Internal resistance mostly 21 to 23 mΩ

    I was trying to run the Dr Prius full battery test but could not finish it because it kept asking for accelerate then decelerate. It did show P0A0F during the test.

    Does this look more like an engine issue than a hybrid battery problem. Anyone seen this combination of codes before on a Gen 2 Prius. Any suggestions on what I should check first would be appreciated.
     
    #1 TechBill, Mar 4, 2026 at 1:04 PM
  2. ChapmanF

    ChapmanF Senior Member

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    Definitely engine. That's what all the codes are about. Nothing there about the traction battery.
     
    #2 ChapmanF, Mar 4, 2026 at 1:51 PM
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  3. TechBill

    TechBill New Member

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    I am googling it now to see which engine issue is more likely cause this. It leaning me toward to dirty or bad MAF or throttle body.

    Bill
     
    #3 TechBill, Mar 4, 2026 at 1:55 PM
  4. saneesh8

    saneesh8 Member

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    P0A0F - I got it on my 2009 few months back. It also had throttle body error. Replaced with junk yard unit($30), worked for few months and then failed. Replaced with new one from local dealer. So far no issues after that.

    There are some rebuild units available on ebay which is cheaper like $100. Dont know how long they will last.
     
    #4 saneesh8, Mar 4, 2026 at 4:38 PM
  5. PriusCamper

    PriusCamper Senior Member

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    Yes, but trying to start an engine that won't start will drain down the hybrid battery to the point of it needing to be re-charged with a grid charger.
     
    #5 PriusCamper, Mar 4, 2026 at 4:41 PM
  6. ChapmanF

    ChapmanF Senior Member

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    The P0A0F code itself doesn't tell you much; it's just the HV control ECU saying "hey, I asked the engine to run, and it didn't." To work out what the issue might be, you have to look at the codes specifically from the ECM.
     
    #6 ChapmanF, Mar 4, 2026 at 4:43 PM
  7. BiomedO1

    BiomedO1 Senior Member

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    So is the engine actually running or idling - or is it just the traction battery cranking the engine????
    How many miles and when was the last engine tune-up/fluid checks?
     
    #7 BiomedO1, Mar 4, 2026 at 4:51 PM
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