Battery control system malfunction following catalytic converter replacement

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.

 

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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?

 

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

 

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.

 

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.

 

Get a new repairer

 

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.

 

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.

 

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.

 

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.

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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.