P0A80 code on Dr. Prius, but not the vehicle

not sure what you mean by 'car reporting it'. how else would doc prius get it?
without tech stream, you can rarely be 100% sure of codes

 

I'm not sure how to read that last sentence. Are there any dash lights? If so, which ones?

Trouble codes can be pending, current, historical, or permanent.

A pending code is one that won't be a warning unless the car sees the same thing happen again. Then it becomes a current code. Some conditions only need to be seen one time and go straight to current. Current codes are the ones that light warning lights.

A historical code or permanent code is one that was current at some time in the past. The car remembers the code, but it isn't current, so it no warning light.

Depending on the scan tool or app you're using, some will clearly tell you whether each code being shown is pending, current, historical, or permanent. Techstream, for example, has different columns to show the codes in.

Some scan tools, maybe, don't show you that as clearly.

 

There's a rare instance when a hybrid battery issue is repaired and the code doesn't clear... That's probably not your problem, but do you know the history of you hybrid battery? In general with Dr. Prius app, you want to follow the "voltage difference" number in the middle as more important than all the other numbers. If that number gets higher than what we're seeing in your screenshot too often, you're gonna need some hybrid battery work and you'll be taking screenshots & clearing the red triangle while driving periodically.

 

If you have a code shown, and there isn't a warning light for it, then it's either a pending code (something that has been recently detected, but not enough times to warn about yet), or a historical or permanent code (something that was detected in the past).

There's a little difference between historical codes and permanent codes. A historical code is remembered just for your convenience, so you know about that code having been present at some point. You can say "ok, thanks, now I know" and clear those codes.

A permanent code is a little different. You don't get an option to just clear it. It only goes away after the problem has been fixed, and the car has completed certain real-world tests to confirm it's really fixed. Sometimes those take a certain amount of driving and under certain conditions.

If I remember right, P0A80 leaves a permanent code. So it'll be there until the car convinces itself the battery is now ok. In the P0A80 section of the repair manual, there will be a "confirmation driving pattern" section giving the exact conditions you can make sure to hit in your driving, if you are impatient for the car to finish deciding the battery's fixed.

 

But what about those rare instances where the P0A80 permanent code never goes away? Some Toyota dealers have suggested the ECU has to be replaced... And professor Joe got it to go away on a hybrid Tahoe by connecting the 12v positive & negative terminal together, but others have found no way to get rid of it... Any additional thoughts on what people with that problem can do to get rid of it? I know it's rare, but it's always an interesting question.

 

I had a permanent P0102 code for a year before it went away. It was a pandemic year, and I just never happened to drive all the necessary ways to satisfy the P0102 monitor. When I finally did, it went away.

In that case, it was complicated because the edition of the repair manual I was looking in actually didn't have all the steps of the confirmation pattern. Elektroingenieur found the missing steps in a later edition.

I could have repeated the incomplete steps in the edition I had forever, and they wouldn't have made the code go away. In the back of my head I was even thinking of replacing the ECM just to get rid of it.

I think having the confirmation pattern be incomplete in the manual is kind of rare, but editorial mistakes do occasionally happen.

A confirmation pattern with steps you don't know, and don't happen to be hitting in your everyday driving, can be pretty much the same as a code that 'never' goes away.

And I don't get the sense dealers have a lot of people well versed in those details. When I was wondering how to get rid of that P0102, I asked about it here, and it was Elektroingenieur who found the missing steps.

I'm pretty sure if I had gone to a dealer and asked "hey, are there any missing steps in this confirmation driving pattern", the most likely first response would have been a blank stare, and the next one would have been "maybe you need to replace the ECU."

 

See:

Toyota Service Information and Where To Find It | PriusChat