2010 disabled - P0A94 Code and "Check Hybrid System" message

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by vtwin_pilot, Dec 5, 2013.

  1. vtwin_pilot

    vtwin_pilot Junior Member

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    Hi all,



    My new-to-me (bought in May this year) 2010 Prius last night suffered what seems to be something analogous to a heart attack.

    Nearing home on my usual 21-mi commute from work and on a secondary road, I was stopped at a red light. As I normally do when at a red light when a rather spirited start isn't needed (no or few cars behind me, not uphill, etc) I pushed the "EV" button to take advantage of electric acceleration up to 25 mph. All seemed normal as the light turned green and I started off. I don't know if I reached 25 or not - must've been close - when all of a sudden the acceleration stopped as if I'd taken my foot off the pedal when indeed I'd not. Simultaneously, a circus of lights lit up on the dash along with the fairly ominous message of "Check Hybrid System."

    As with all things electronic these days, I figured a good ol' fashioned reboot was in order. Turned it off and back on and...same thing of course. Being near an intersection and a very bad place to be stopped - and not knowing if the car would actually move - I pressed the accelerator anyway, despite the warning lights, and indeed the car started to move. It seemed to cap the speed at 12-13 mph, which immediately seemed like some kind of self-protective safe mode. Luckily, I was within spitting distance from home, so I limped the last 1/4 mile in this state - and at 12 mph.

    There are probably 5-6 warning lights on in addition to the big "Check Hybrid System" message. Let's see, first and foremost, the yellow triangle of death, followed by what I think is the Slip indicator (car icon with wavy lines), the CEL, the encircled exclamation point which I think is the braking system, and I forget, a couple of more. I should've snapped a pic but I was in a hurry to troubleshoot.

    So I used my Actron scanner to pull the P0A94 code. I didn't see that it's able to read the sub codes, or maybe that's a capability that only the expensive dealer scanners have. Anyway, after much googling on this forum and in general, I can't conclude what it is other than the generic "DC-DC Converter Performance". I know that here and elsewhere there's a list of all DTC codes, and I saw that this code has 17 sub-codes, many of which are related somehow to the inverter, which seems to have been the subject of a recall in Gen II models (acutally the inverter cooling pump IIRC) but not on Gen III.

    I just set up a tow to get it to a local Toyota dealer, so as of now I don't know anything yet. It should arrive to the dealer later today so I'd expect a first diagnosis sometime tomorrow and I'll post up as this unfolds. Given the hybrid system is warranted for 8yrs/100K mi, I'm guessing/hoping that all this is covered under warranty, but we'll see.
     
  2. retired4999

    retired4999 Prius driver since 2005

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    My guess, maybe inverter water pump. Could you see circulation in the reservoir?
    Lets us know what you find out!
     
  3. David Beale

    David Beale Senior Member

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    My -first- guess would be the 12V battery. It's the most likely thing to fail, particularly at the age of your car. When it gets "iffy" it causes all kinds of false codes to come up. But I'm sure the dealer will tell you.
     
  4. Spindifferent

    Spindifferent Member

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    +1

    Same thing happened with my 2010; 12v battery had a bad cell which prevented the car from being started. Car had to be towed into the dealership. Fortunately, battery was within the warranty period and was replaced for free.
     
  5. vtwin_pilot

    vtwin_pilot Junior Member

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    You know, it never occurred to me to check the 12V battery. I guess when I pulled the code I did, it guided me down the path it did (inverter) rather than something like the battery. But of course it's all an interconnected system and a wonky battery can certainly produce odd symptoms.

    Well, in any event, the dealer just called and said that it's the inverter and that it's covered under warranty. I didn't ask on the phone, but when it's done and I pick it up, I'll have to ask if it failed as a result of anything due to the inverter coolant pump, but I'd hope and pray they're competent enough to make that determination (big leap of faith sometimes, I know).

    What's striking about this issue is just how quickly the car went from being normal to being disabled. My family and I drove this car roundtrip from Atlanta to Lakeland, Fla and back for the T'giving holiday, and holy smokes would it have sucked to get stranded somewhere in B.F.E. miles from nowhere on a holiday weekend. That it crapped out so close to home is total luck. But more to the point, I'm curious if anyone has some insight as to why, when there's an issue with one of the two motive systems in this car, the other one doesn't take over. Now, I know the regular (non plug-in) Prius is not meant to be a full electric vehicle capable of everyday driving, but I would have thought that even under duress as it was, I'd've been able to drive at 25 mph as it normally does. Obviously the engineers designed in a safe mode to cap speed around 12 mph when the electric side goes bad. But why don't they allow it to be run entirely by the ICE? Given it's a "synergy" drive, I thought it was able to run on all electric, all gas, or a combo.

    Well, that's just an intellectual exercise. The main thing is that it'll be fixed soon. But of course, in my mind, I'm already thinking "Will this happen again when this is out of warranty?" If it did, that cost would likely wipe out several years' worth of gas savings that make it such an attractive option.

    I'll post up again when I get the car back and a final conclusion.
     
  6. jdcollins5

    jdcollins5 Senior Member

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    There have been a few other inverter failures reported on here but not many. You were just one of the unlucky ones as far as having the failure but mighty lucky to have had it fail close to home and be covered under warranty.

    The ICE and the HV electric system were designed to work together for maximum efficiency and mpg. The down side of this is that the Atkinson Cycle engine does not develop enough torque at low speeds to accelerate the car. The car accelerates up to about 15 mph with the electric motor MG2 until the ICE can develop enough torque to start helping. So when the inverter fails the system goes on to Limp mode.

    It would be a similar situation if the ICE were to die. You need both systems to work.
     
  7. vtwin_pilot

    vtwin_pilot Junior Member

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    I didn't realize the Atkinson engine wasn't torquey enough to start the car from a stop. As I'm new to the Prius, I've watched the HSI as I drive and I'd noticed, as you said, that it accelerates from as stop via electric up to about, at least in my car, 10-12 mph before the engine kicks in. I thought the electric assist was just to take a load of the ICE and improve mileage. I learn something new every day!

    I got the car back and it was indeed the inverter and all was covered under warranty. I paid absolutely nothing. The service advisor at the Toyota dealership told me he's seen several failed Prius inverters. When I asked him how much it'd've been if not under warranty, he blurted out rather quickly "around $5K". I thought I saw another post here or elsewhere where the poster had a copy of the invoice from the dealer and it was around $3K. Either way, it's one expensive repair and hopefully anyone else in the future who experiences one will have had it happen within the warranty period. I also did ask if they suspected any ancillary causes such as a bum inverter water pump and he said all checked out. I'll trust that they did check it but still verify it myself.

    Thanks all for your responses.
     
  8. you_should_contra_dance

    you_should_contra_dance Junior Member

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    I have a 2010 prius with 66k and my power inverter went out just last week. under warranty, so no charge to me. Out of curiosity I asked the guy who had called from the service department how much it would have cost me if it had not been under warranty. He said Oh about 10k. However I just did a search for the part number G9200-49025 and found it really the part itself costs more like $2500.
     
  9. jdcollins5

    jdcollins5 Senior Member

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    From the 2010 Prius Parts Catalog. I am not sure what the difference in part number above. That may be just the inverter module and not the assembly as listed below.

    Inverter Assy - G9200-47140 - $2,658.42
     
  10. Umar Ali

    Umar Ali Member

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    these increased number of cases with failed inverters is worrying me now. and the reason is that i bought mine at 71k in august this year and by december im at 87k because i have to drive 200miles commute five days a week and at this pace ill cross the warrenty in about 3 to 4 months. is there any specific reason to why it failed which i can do preventive maintenance on?. i change oil every 10k with toyota full synthetic 0w20 myself and also changed transmission fluid with toyota ATF about 12k ago and about to change again in about 1k just to flush it. whatelse needs maintenance or i should keep eye on to prevent this hefty repair situation out of warrenty?
     
  11. jdcollins5

    jdcollins5 Senior Member

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    If you have not changed the engine and inverter coolant it would be good to do. These are two different coolant loops but they use the same Toyota LLC coolant.
     
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  12. Umar Ali

    Umar Ali Member

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    Ill defintely get onto that, i hope there will be some DIY for that too.
     
  13. jdcollins5

    jdcollins5 Senior Member

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  14. you_should_contra_dance

    you_should_contra_dance Junior Member

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    my repair guy said the inverter coolant on a 2010 prius should be fine for at least 5 years, so it's too early for that to have caused the problem. I just had a defective part, I guess.

    In terms of the part number, which I said was G9200-49025 , I suspect they gave me the updated model, rather than the one listed in the 2010 manual (G9200-47140). The reason I suspect this is that, with the new one, whenever I issue a command to the display via the steering wheel buttons, the dashboard lights up with the current choices, in a way it didn't before.
     
  15. Umar Ali

    Umar Ali Member

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    What do you mean by choices it didnt give before? can you take picture or tell what is different from previous one? is it possible that they put in the 2013 model firmware version which has few more options like cost and drived distance when you turn off the car as it wasnt present in 2010 model.
     
  16. jdcollins5

    jdcollins5 Senior Member

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    Most on here would disagree with the statement that the coolant is good for 5 years. That is not saying that the coolant caused the failure. If you want to be proactive in maintaining your car the advice would be to change the coolant on a more frequent basis.

    I changed mine at 50k miles and will do so again at 100k.
     
  17. macman408

    macman408 Electron Guidance Counselor

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    It's not really the engine's fault; it's the gearing. The engine is hooked up to the wheels with a single gearing ratio - so running only from the ICE would be a bit like trying to drive a stick shift using only fifth gear. If it had a different fixed gearing ratio, it could probably run on the ICE alone in a limited range of speeds - but then it wouldn't be terribly efficient.
     
  18. Pdaddy

    Pdaddy Member

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    I have the code POA94 as well with all my power assisted warning lights going off while driving (antilock, brake system, master, check engine) Is there significant difference between DC inverter parts GD9200-47140 and G9200-49025 listed above? I need to replace the inverter and there is a big difference in cost between the older and newer (?) parts. Also would I need a computer update after switching parts out?

    In addition, I have an the original 12 v lead battery which must be about 7 yrs old. How long should this last? regular car batteries last maybe that long if I am lucky.
     
  19. m.wynn

    m.wynn Senior Member

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    If you are in the U.S., head for your preferred dealer. P0A94 is warrantied for 15 years/unlimited miles. So long as the vehicle is not salvage title, they will repair your inverter for free. In answer to your question, the part they will replace is the Intelligent Power Module. Not sure of the part number...
     

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  20. Pdaddy

    Pdaddy Member

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    Thanks for that. I have seen two warranties online but not this letter. I have seen one for 2012 -13 or 14 with same coverage as the letter and another for my year that states replacement only before the ECU update which I should have had. I called the dealer and they were not helpful--which means I take it in and they run the diag and charge me $80 or more if its not covered.
     
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