P0B42 code on 2010 Prius 2 with 191k

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by pairoPriuii, Sep 1, 2021.

  1. pairoPriuii

    pairoPriuii New Member

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    The car was running fine with no degradation of mileage or performance when the Triangle of Death appeared along with the message "Hybrid System Requires Attention". I was able to drive home without incident (sans regen) but the next day the ICE would not start and the car would not move. After ordering a bluetooth OBD code reader and downloading Dr Prius software, I determined HV battery voltage was low and decided to bite the bullet and try equalizing the individual modules. $700 and three charge/discharge cycles later I got all modules above 16 volts and the pack voltage up to 235 with the charger connected and 225 to 229 while driving. The ICE runs continuously but the dash display dose not indicate any power flowing between the motor/generator and HV battery.The only code it throws is POB42. Can anyone tell me what that means beyond "Hybrid System Requires Attention?
     
    #1 pairoPriuii, Sep 1, 2021
    Last edited: Sep 1, 2021
  2. bisco

    bisco cookie crumbler

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    have you opened up the battery? might be corrosion, very common
     
  3. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Can you share more specfics, this was the Prolong charger, or?
     
  4. tankyuong

    tankyuong Senior Member

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    Needs new battery
     
  5. Grit

    Grit Senior Member

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    i was going to suggest check if hv battery is still under warranty first but looks like there’s good advice ahead already.
     
  6. ChapmanF

    ChapmanF Senior Member

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    Sure. A quick look in the repair manual (more info) shows it means that a voltage reading less than 2.5 V was seen for the second battery block.

    Note that this is not the kind of code that tells you a battery module is tired and worn out and you need a new battery. The battery blocks (pairs of modules) have nominal voltage of 14.4; dog-tired and worn out would still be above 10.

    A voltage reading less than 2.5 V means that the voltage reading itself is just wrong. Usually it means that voltage sense skinny wire (the one to block 2 in this case) has corroded or snapped off, or the connector where those skinny wires connect to the battery ECU is suffering from corrosion.

    That kind of problem generally can be completely solved by repairing the battery, not replacing it.
     
  7. pairoPriuii

    pairoPriuii New Member

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    My mistake, the DTC is actually POB080, not POB42 ... I have opened up the battery and cleaned up the bus bars and nuts. Yes, using the Prolong charger and automated discharger.
     
  8. pairoPriuii

    pairoPriuii New Member

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    Yes, found some corrosion on bus bars and nuts, cleaned them and reassembled but no joy.
     
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