Dealership says I need a new HV battery AND ALSO that I need a new battery ECU. True?

Discussion in 'Gen 2 Prius Main Forum' started by MarkM123, Jun 2, 2025 at 6:04 PM.

  1. MarkM123

    MarkM123 New Member

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    2007 Prius in good condition with 100K miles.

    The notes from the dealership following a $210 diagnostic test say:

    "HV DTC P0A80 Replace HV battery Pack. Found HV battery block #7 at 14.2V while all others at 15.5v 1.00 Replace HV battery and HV ECU due to overheated connectors."

    Is "overheated connectors" a real reason to replace the battery ECU?

    Quote:
    New OEM battery + installation = $3,438
    New battery ECU + "free installation" with battery = an additional $1,483

    It's the second battery to fail. My usual mechanic, who I trust only slightly more than the dealership, replaced the original battery that came with the car in 2022 with a remanufactured battery that lasted 3 years. Reading priuschat.com and the Prius subreddit has convinced me that if I'm going to replace the HV battery, I should get an OEM, not a rebuild.

    I can stomach $3,438 for a new OEM hybrid battery if I'm going to get 200k+ more miles out of the car, but somehow that extra $1,483 seems like too much. OTOH why quibble over $1,483 if it means more certainty that the car will work properly.

    I respect this forum greatly and look forward to your recommendations.
     
  2. PriusCamper

    PriusCamper Senior Member

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    A new battery ECU cost $800 a few years ago and a battery pack cost $1900. The ripoffs at the stealerships are soaring to all new heights...

    Meanwhile a used battery ECU for your Prius is available on Ebay for $100... Alternatively you could go with a company like hybrid2go or greenbean or greentechauto and they'll install a rebuilt pack with a warranty and the ECU will be part of the pack they swap out at no charge to you. And granted the days of lifetime warranties are over from these folks, but the convenience of them showing up and swapping out a pack under warranty free of charge, with no ECU worries, in less than an hour is a great deal.

    There's other more affordable options too, like my buddy professor Joe is selling gen2 battery packs with Gen4 (2016-2022) modules for $1800: Refurbished Hybrid Batteries | About us | 2nd Life Battery It'd be worth finding out how soon he's back in stock of those packs because they're as close to new OEM as you're gonna get.

    And because you're in the same state as me, maybe you live close to me in the Olympia area? I got all kinds of packs to choose from in just about every type, except brand new OEM. I got a couple OEM packs from Gen3 Prius that haven't failed yet that I'd give you a ridiculously low PriusChat discount on.

    In other words I'd save your money and not give it all to the stealership when so many other afford options exist, especially because NiMH battery chemistry is inferior to the performance of Sodium-Ion in every way. It's one of the only ways you'll get a sense that you upgrade the all around electrical performance of your Prius.

    I'm also a certified installer for sodium-ion battery packs and can give you a really great price on an install and unlimited tech support if you use my affiliate link in signature below.
     
  3. bisco

    bisco cookie crumbler

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    why not have your mech install a new oem?
     
  4. MarkM123

    MarkM123 New Member

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    I asked the mechanic for a quote with several options and they came back with a $3K (installed) option for a remanufactured with a 2 year warranty, and an "all new" cells option with a 4 year warranty for $4K installed. Talking to the service rep about the latter, he gave away the fact that it was a greentec battery! I can get the greentec directly from them for $2700 installed. Not a great endorsement for the independent mechanic shop.
     
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  5. MarkM123

    MarkM123 New Member

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    I did ask the shop about an OEM option and they said it would be more expensive, with only a one year warranty. So much for that. If the dealership installs an OEM, there's a three year warranty.
     
  6. Tombukt2

    Tombukt2 Senior Member

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    To be honest about it the battery ECU usually gets cleaned and is fine generally I e a few hanging round . Unscrew silver back clean up the mess no broken pins wella. That crap must be clean of the powdery crap
     
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  7. xw20_driver

    xw20_driver Junior Member

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    Dealership and most reputable Prius hybrid specialist shops likely will recommend a battery ECU along with the new HV battery. The ECU orange harness pins seem to have a common corrosion problem. Typically, the 3 ECU pins are heavily corroded and the orange harness will show signs of burnt marks. They're selling the service, labor, and warranty. A new ECU paired with a new battery increases their profit margin and also service reliability so that you don't come back months later with trouble codes because the old ECU failed or glitches out. The technician isn't going to open the old ECU and do bench work on cleaning and refurbishing corroded pins.

    Dealership shop will not touch any used parts. A new ECU part 89890-47092 runs at least $1K. Used pulled units seem to cost around $100. When the dealer installs the new OEM HV battery, the ECU, main relays, terminals, etc all come off as one unit from your current pack and moved into the new battery pack. The ECU can be easily swapped out while they do this work.The new battery includes the brand new battery harness.

    A independent hybrid specialist shop who is willing to sell a brand new Toyota OEM HV battery for $2300 OTD also recommended that I inspect the ECU and either replace with a new part or find a good condition used part.

    Old thread RE cooked ecu pins: Gen 2 Traction Battery ECU board connector replacement | PriusChat

    DIY ECU connector replacement: The battery fires at ECU sense connector thread | Page 8 | PriusChat
     
    #7 xw20_driver, Jun 4, 2025 at 11:54 AM
    Last edited: Jun 4, 2025 at 12:25 PM
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  8. MarkM123

    MarkM123 New Member

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    This is all very helpful. Thank you.
     
  9. pasadena_commut

    pasadena_commut Senior Member

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  10. Tombukt2

    Tombukt2 Senior Member

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    I think chap or somebody well versed in electronics world should be able to know how to get orange it can be done . It may be different color .
     
  11. bisco

    bisco cookie crumbler

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    getting orange can be a challenge
     
  12. PriusCamper

    PriusCamper Senior Member

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    If you're buying a brand new OEM pack the warranty is irrelevant on the physical pack its going to go 10 years or longer without issue. I've never seen an exception to this yet other than in the early 2000's for reason I won't go into. However if a shop installs a pack and they screwed up the install, having a warranty on the work would be wise.

    Currently shops are trying to get away from new OEM packs because the prices are so high from the Toyota they can't add much on top of that to cover their purchasing and pickup costs. Nexpower, for example, is primarily selling Sodium-Ion packs in bulk orders to shops these days because their customer service costs for DIY installs are huge and the current demand from shops wanting to stock up on spare packs for the Summer months is way higher than individual buyers.
     
  13. Aegean

    Aegean Active Member

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    Another option is to sell the 100k Prius as is for $2000, plus the $5000 you are ready to pay the dealer and use the $7,000 to get a newer Toyota. Especially if you like to add a couple of thousand more to get a low mileage 2014+.

    Is the paint excellent, interior nice and tires new? Remember it still will be an old car with high risk for other repairs like the expensive brake actuator or an AC evaporator.
     
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  14. PriusCamper

    PriusCamper Senior Member

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    Lol... You obviously don't live on the west coast... A 2007 Prius with only 100K miles are still selling for $5K out here. If it were my car I could swap the pack with a spare and fix all the little things and likely get as much as $6K for it.

    As always, people who use PriusChat as a DIY resource can usually get a super affordable fix and people who depend on the auto repair industry in its current state are likely going to be faced with repair quotes costing more than half the value of the car.
     
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