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Battery control system malfunction following catalytic converter replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Priusowneritech2006, Oct 4, 2022.

  1. Priusowneritech2006

    Priusowneritech2006 New Member

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    Dear users,
    I am located in Australia and have a 2006 Prius i-tech with 190000 kms. It has never had a major problem or required major repairs.
    Unfortunately, the catalytic converter was stolen from it a few weeks ago. I took it to my mechanic who found this problem and also noted the post catalytic converter wiring was damaged. I contacted my insurer who took it to a smash repairer they work with and the catalytic converter was replaced.
    The car functioned normally for about a day. Then the check engine light came on but the car appeared to be functioning normally. I took it back to the smash repairer, his mechanic checked it out and said the cat/O2 sensor was working fine, system needed a reset which he did by unplugging the 12V battery briefly. Light went away and the car drove normally.
    The light came back and another mechanic scanned it and found the P0420 error code - catalyst system efficiency below threshold (bank 1). They advised non urgently taking it back to the smash repairer.
    About a week later when starting the car multiple new warning lights came on - the red triangle light, VSC, yellow circle exclamation mark and the red car exclamation mark on the touch screen display. Insurance took it back to the smash repairer. I've just heard from them today. They have had it for several days and are confident the catalytic converter and O2 sensor are working normally. They are saying there is a "battery control system malfunction" which is not related to the repairing of the catalytic converter. I am now potentially looking at thousands of dollars to replace the hybrid pack in addition to the $850 excess I have paid so far. I find it hard to believe that this system issue coincidentally is present? Particularly as there were warning messages immediately after the repair.
    Is anyone aware of this problem occurring either due to damage related to the removal of a catalytic converter or a computer system issue post installation of a new catalytic converter? I would very much like to push for any additional repairs to be covered under my insurance claim. Alternatively, are there other options than replacing the whole hybrid pack ie could it be a computer system issue related to the new catalytic converter? (this has been alluded to by the mechanic who found the P0420 error code).
    Thanks so much for your assistance, this has been going on for weeks and I am struggling on my own.
     
  2. JC91006

    JC91006 Senior Member

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    The problem with P0420 is almost 90% always a bad catalytic converter. So I would insist on having an OEM original part installed along with an OEM original Denso O2 sensor. Since the insurance is paying you should demand the original stuff that actually works on the car.
     
  3. dolj

    dolj Senior Member

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    Hi and welcome to PriusChat.

    (FYI, your posts are moderated so we do not see your posts until a moderator approves them. This is an anti-robo spam mitigation measure.)

    Sorry to hear catalytic converter theft has reached Sydney. It is a plague.
    You don't say what codes were pulled immediately after so a judgment is not easily made. What were the codes at various stages of your saga? You can't read the codes once and assume that if the light (or lights) pop up again that the codes are the same as the previous ones.
    What catalytic converter was installed? Toyota OEM or some kind of aftermarket?
     
  4. Priusowneritech2006

    Priusowneritech2006 New Member

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    Thanks for your message dolj. Unfortunately I don't have all the error codes.
    At initial assessment I was told - CATALYTIC CONVERTOR CUT OFF AND POST CATALYTIC CONVERTOR O2 SENSOR WIRING DAMAGED
    After repair when the check engine light came on I was with the mechanic when he checked it out, he said the 02 sensor and the catalytic converter were working fine. Reset the system and never told me an error code.
    When the check engine light returned a few days later it was the P0420.
    I am waiting for the full brief on all the error codes this time, and will also find out which catalytic converter was installed.
    I will report back when I know this information. Thank you kindly.
     
  5. Another

    Another Senior Member

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    Aren’t there two O2 sensors? Did they replace both with OEM?
     
  6. Tombukt2

    Tombukt2 Senior Member

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    Lotta Mile's on car . Car sat awhile too weeks you're HV battery is coming on 15 years . So it is getting time or VERY close to time. Oraybe for some newer car time . But not for me . I'd get to looking into battery options . Should be many. You can use various Apps to look at battery electrically. Mite be a good idea. Dr Prius comes to mind . My Aussie buddies who I was on Toyoda mods with some 23 years would have this sorted in a few days or hours . I'm sure they're alot of options in Aus. Maybe talk to some local Toyoda folk on . ToyMods site . Many of you fellows they're . It's called the Toyota modifications list or Toyota modification server it's been up and running probably close to 25 years.
     
  7. TMR-JWAP

    TMR-JWAP Senior Member

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    Here's an explanation that may make a bit more sense to you.

    Let's assume the troubleshooting is correct and the car has thrown codes for the hybrid battery. This would normally be a P0A80 + the possibility of another code identifying which set of modules inside the battery are causing the problem.

    It's not the catalytic converter work itself that caused this, it's the idle time while waiting for the repairs. Once a hybrid battery gets some age and miles on it, (as with all rechargeable batteries) they develop some internal discharge problems. Basically, if you let it sit unused, it tends to lose its charge. Your hybrid battery is made up of 28 small batteries connected together inside the case. All it takes is for one of those small batteries to self-discharge enough that it's seen by the ecu as being "out of balance" with the others and triggers a code. If the car is driven every day, it's likely this self discharge problem can stay in the background for years, as the battery gets charged everytime you drive it. It's kind of like adding air to a tire with a slow leak. You'll never have a flat tire if you add a little air every day. Let it sit for a week or two, and the tire will be totally flat and may be damaged from the weight of the car sitting on it and the rim pinching the rubber. Let the HV battery sit idle for too long, a module(s) may "go flat" and could be permanently damaged to where it doesn't recover, even after being charged.
     
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  8. Priusowneritech2006

    Priusowneritech2006 New Member

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    Thanks for everyone's help. I have some further information. The current error codes are P0A80 and P3000.
    The repairer did not use an OEM original catalytic converter or an OEM Denso oxygen sensor. He said that they are discontinued and are unavailable to get. So he used aftermarket parts.
    The repairer seems to have the same explanation as TMR-JWAP regarding the current faults. He puts down the hybrid system as the reason the P0420 error code was appearing as well.
    Hope this is helpful thanks for everyone's help.
     
  9. Another

    Another Senior Member

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    Get a new repairer
     
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  10. Tombukt2

    Tombukt2 Senior Member

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    It takes some time to get up to speed on all this coding etc . But generally it's not long. And once you start to get the hang of it like all things appliances and etc most brands have their specific common faults and common things happening that people either help happen or that just happen on their own just read through any car list and you'll see that with any making model that is kind of a help The rare things that you read about here were people going around in circles with things generally are not real common. Or they become this vicious cycle because some of the thinking being used is stuck in a really small square box possibly.
     
  11. ChapmanF

    ChapmanF Senior Member

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    Partial credit to that repairer, then. Trying to pin the P0420 on the hybrid system is just as goofy as trying to pin the P0A80 on the catalytic converter. They're just two different issues the car happened to have.

    Those codes don't even come from the same computer in the car. P0420 comes from the engine control module, and P0A80 comes from the battery ECU. As you might expect, the ECM doesn't know jack about the battery, and the battery ECU doesn't know jack about the engine or catalytic converter.

    There is a little bit of gossip that goes on between the car's different computers. For example, the HV control ECU can set a P3000 code because it heard the battery ECU saying P0A80. And the brake ECU can set C1259 and C1310 because it heard there are codes in the HV ECU.

    But for the most part, each ECU just sticks to giving its own trouble codes about things in its own area of responsibility.
     
  12. Priusowneritech2006

    Priusowneritech2006 New Member

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    Right I see. Well to be clear the P0420 code was detected a few days after the aftermarket catalytic converter and O2 sensors were put in. P0A80 came later. Repairer is claiming the cat and 02 sensor are working well. Just said that "all sorts of codes" can come up when there is a battery problem.
    Is it possible the aftermarket car/02 not working properly, or at least the car computer thinking it wasn't working properly, would then lead to discharge problems with the battery and eventual failure ?
     
  13. Priusowneritech2006

    Priusowneritech2006 New Member

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    Aftermarket cat* sorry
     
  14. ChapmanF

    ChapmanF Senior Member

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    That wouldn't be my first guess. I think TMR is probably closer; if the battery's old and borderline P0A80, and the car sat around a while for the cat work, sitting around could have nudged the battery across the line. It's possible that if you do some more driving and get it well charged again, that'll nudge it back and you won't see P0A80 again for a while, but that's just how things are on the borderline.

    The ECM sets P0420 when a catalytic converter has less than the minimum acceptable oxygen storage capacity. The car tests this while you are driving: if you are cruising along for a while, the ECM will sneak the mixture a bit lean for a short time, which means extra oxygen in the exhaust that the catalyst will capture and store. Next, the ECM will sneak the mixture rich for a short time, but the downstream O2 sensor won't show that immediately, because of the extra oxygen stored in the cat. The longer it takes for the O2 sensor to show the change, the more oxygen the cat was able to store, the better. When that storage capacity gets too low, P0420 gets set.

    Some aftermarket cats just never have enough oxygen storage capacity, even right out of the box, to pass that test.

    Unlike some trouble codes, where there is some fail-safe change in behavior because the issue might otherwise result in some damage, a P0420 code doesn't really change how the car behaves. It is just telling you about not being able to meet its emissions goal.
     
  15. mr_guy_mann

    mr_guy_mann Senior Member

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    One possibility for a P0420 is that there is a (small) exhaust leak at the cat that's affecting the reading of the downstream O2 sensor. That could result in a false failure.

    More common is that the AfterMarket cat (& maybe the sensor) are not up to the standards the OE Toyota cat. An AM cat can "work" but not have enough oxygen storage capacity to pass the ECM's monitor test.

    In that case, if you want/need the check engine light to stay off, then you have to get a "better" part installed. At my shop, I have pretty much given up on using AM cats - unless it is impossible to get OE from a dealer.

    Posted via the PriusChat mobile app.
     
  16. Tombukt2

    Tombukt2 Senior Member

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    If you were to put the car on an exhaust gas analyzer your cat is probably working very well your car's ECU is programmed in such a way that it doesn't think so 02 Corollas had the same problem with the AC Delco American computer The 202 sensors were were programmed in the eProm too tightly and after 70,000 mi or something you'd have the check engine light the rest of your life. Matter of fact my O2 Corolla sitting in the yard out here if I was to start it up to check engine light comes right on and it tells me that my catalytic converter is something similar to below threshold like the Prius. There was a flash for the Corolla computer I just never bothered with it AC Delco has no business in the Toyota.