P0A08 code help and hybrid health check questions.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Cybervic, Dec 3, 2020.

  1. Cybervic

    Cybervic Junior Member

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    2007 Prius
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    N/A
    My 2007 Prius mk2 has done 99.7K. It used to do 100-150 miles per week but has been sitting a lot this year because of covid. I had to replace 12v battery in July after we came out of lockdown (I'm in UK). Car had been jump started prior the battery replacement with correct polarity.

    This Monday the Red warning triangle came up when I was moving the car out to middle of the road from home. While I was trying to do a 3-point turn to get back home, VSC and (!) light came on too along with a very light beeping sound. I went home to google some trouble shooting steps, came across some posts saying water leak near 12v battery may be an issue. I went back out and checked around 12v battery and HV battery cable and they all seemed fine. I put the trunk storage box back in place, switch on the engine. The red triangle has gone.

    I was very puzzled and bought a cheap OBD2 scanner. No code was found. Took it for a short drive, HV battery charged up ok according to display screen and car drives alright too. The car was due for a hybrid health check 2 days later. I went and it failed because there's a P0A08 code.


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    12v battery reads 12.4V (power-only) & 14V(ready mode) from self-diagnostic menu. I'll check fusible link and water pump turbulence when the rain stops tomorrow. I've got some questions I need some help with answers please.

    1. The guy at toyota service desk said a bad DC convertor prevents any reading on Hybrid battery, hence it's n/a on the report, is this true?
    2. Is it possible the DC convertor is bad without any red triangle warning?
    3. If my DC convertor is gone, is there any tips pick up a second hand one? UK ebay has them from £85 to £250, can I just buy the cheapest one?
    4. Is it safe to drive in the mean time, when there's no red warning sign?
    5. In recent weeks, my car has had a oil change, new rear disc and brake pad. Could any of these trigger the code/red warning although I've driven 70 miles before the problem occur.

    Thanks in advance.
     
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    The Toyota Repair Manual shows that a P0A08 will allow the car to continue driving normally. The troubleshooting guide does mention loose connections on the battery cables can cause it, among many other connectors.
     
    #2 TMR-JWAP, Dec 3, 2020
    Last edited: Dec 3, 2020
  3. rjparker

    rjparker Senior Member

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    That English rock star of the early 1600's may have written about this in his million seller Much Ado About Nothing.

    Seems to me if you are running and driving with 14v while in Ready, your dc to dc is functioning and the hv battery is running. Maybe there was a code and you cleared it if you pulled the cable off the 12v battery.

    I would get a better scanner, maybe a bluetooth scanner with an app like Dr Prius. Then wait for a recurrence.

    By the way, run the car for a few miles every week. Sitting for long periods is bad for Prius battery systems.

     
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    Do a search for P0A08 on the forum. It has been known to be an PITA to narrow down. Possibly bad ground connections in 12v wiring harness, 12v battery connections, various plugs etc. Repair manual lists a bunch of things to check. For the OP, the car should continue to operate normally. Personally, I would do some quick inspections of any wires/cables that may have been recently touched and continue driving it.
     
    SFO likes this.
  5. Cybervic

    Cybervic Junior Member

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    Location:
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    Vehicle:
    2007 Prius
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    N/A
    Thx guys, I've picked up a Carista Bluetooth OBD2, Basic scan says no code found and the advance diagnosis is not support on gen 2 Prius. Can you recommendation any iOS app suitable for Prius mk2? I'd really like to know if the code was current or in the past.

    I have also used Dr. Prius and can get readings from battery. I don't understand why Toyota couldn't get any readying only battery health check. Are they just being lazy? picked up a code in the past and just quote for the most expansive repair.
     
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