Advice Needed - P0AA6, No Subcode on 2005 Prius: Sell or Fix?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by MoofBoof, Apr 21, 2020.

  1. MoofBoof

    MoofBoof New Member

    Apr 11, 2020
    Los Angeles
    2005 Prius
    Hi Everyone,

    I've combed through PriusChat a few times over with great admiration for everyone's curiosity and troubleshooting skills. I know my issue has come up time and time again, but for good measure I thought I'd get this community's perspective on what to do with my car:

    P0AA6 - 526 (2 auto shops weren't able to pull the subcodes)
    When this error first came up, we got it towed to the shop and they saw the P0AA6 code but it disappeared after jumping the 12V - they then reset the car to try to pull subcodes to no avail and told us to drive it until it happened again. A week later after driving it a few times the warning lights came up again so we drove it straight to a 2nd shop (same issue, couldn't pull the subcodes). It's been a few days and we've driven it 150 miles with no issue but we expect it to come up again and have a basic OBD scanner to reset the codes, so we don't get stranded.

    -2005 Prius with 217,000 miles
    -On 3rd HV Battery (last one was a refurbished one installed 2 years ago)
    -3 year old 12V Optima, that's sitting at 12V resting (probably needs to be replaced)
    -Regularly serviced/maintained and original owner
    -Had inverter pump replaced as part of warranty in the late 2000s
    -No weird noises coming from the car
    -Currently using high mileage synthetic oil - which it goes through faster than it did before
    -Wishful thinking that this is the issue, but last night we did seal the noticeable cracks on the rooftop after noticing stains from water building up in the 12v battery compartment and the spare tire compartment
    -In the last five years, I've spent quite a bit of money fixing different issues on the car

    1. Is it safe to keep driving this by resetting the P0AA6 code should we decide to ride this until it dies?
    2. The 2nd shop offered $1,200 for the car as is and most other shops have offered $400 for parts use. Should I cut my losses now and sell it?
    3. Is there any chance a dying 12V or water leakage could throw a false P0AA6?

    I have a strange emotional attachment to this car which is why I've put so much money towards it but it's lived a good life and I want some opinions on whether it's worth it to fix it further when those fixes could be 3-4x the value of the car.

    Thanks so much!
  2. bisco

    bisco cookie crumbler

    May 11, 2005
    2012 Prius Plug-in
    Plug-in Base
    it's always worth trying a known good 12v and see what happens. take the optima to an auto parts store for a free load test. maybe it's bad, maybe it just needs a charge.

    a good 12v should rest around 12.5-9, but what it drops to under load is what the computers see.

    you probably need a prius scanner for the sub code. it will help find where the high voltage leak is.

    a rebuilt battery is the usual suspect, but not an absolute. you could open it up and check for corrosion and wiring issues.

    you can also get the dr. prius app to see if a module is out of whack.

    check out hometown hybrids youtube video on P0AA6, it is very informative. or take your car to a real hybrid mech, i know there is at least one in LA
    #2 bisco, Apr 22, 2020
    Last edited: Apr 22, 2020
  3. dolj

    dolj Senior Member

    May 14, 2012
    Wellington, New Zealand
    2006 Prius
    526 is a sub-code, but there should another one in the 611-614 range. As bisco said HV (hybrid vehicle) battery is most common and a 612 sub-code will confirm this and directs your attention to the HV battery.
    You could drive for 4 years or more by resetting the code, but you could also have a module (inside the battery) explode next month. Even so, it is probably safe, but if the latter happens, it will make a heck of a mess inside the battery case to clean up for whoever draws the short straw. It might stink out the car, too! $1,600 for a new set of after-market modules from or $2,250 - $3,200 for a fresh new set of OEM modules from a conveniently located dealer service center. With a range like that is pays to shop around the dealers in your area.
    Pretty much nope. But 12 V check and (if required) maintenance is never a bad idea.

    Question 2 is pretty subjective, but if the car is in excellent cosmetic condition, otherwise mechanically sound, and you see yourself driving it for another 10 years, you might consider further spend into it. Otherwise, consider parting ways and upgrading into something newer.
    #3 dolj, Apr 23, 2020
    Last edited: Apr 23, 2020
    MoofBoof likes this.