Prius v: Multiple Warning Lights, Hybrid Battery Code, but 12v Disconnect Fixes it. Huh?!

Hi all. I'm trying to avoid a trip to the stealership. Any help would be much appreciated. Buckle-up for a long, detailed description...

2013 Prius v
160K miles
Still consistently getting over 50MPH
Brand new 12v battery
Intermittent problem described below has been going on for about 4 months.

PROBLEM: Upon startup, I am greeted with a fabulous array of 4 warning lights:

slip indicator
brake system
check engine
hybrid system warning

(I have discovered different people sometimes use different names to describe these lights, so I am providing specific pictures to make sure we are all on the same page.)

TRIED SIMPLE THINGS FIRST: Inspected the 12v battery and noticed a lot of corrosion on the negative terminal. Cleaned it up, put it back together, the lights went away and I was able to drive it for several days with no issues and optimal energy performance in excess of 50MPH.

ISSUE RETURNED: After a few days, the issue returned. This time I let it run for a while and did the following:

-Checked turbulence of the inverter coolant reservoir. It had slight turbulence, not a tsunami. But my understanding is that's quite normal for this model. No coolant movement whatsoever in engine coolant reservoir, but not really sure if there should be. So, motivated by hope & prayer beads, I disconnected neg. battery terminal, let it rest, reconnected it, and the car functioned like normal again.

IMPORTANT POINT 1: When these errors light up, the ICE is idling continually. It never switches over to electric mode. Also, pushing the EV or ECO selector buttons on the center console has no effect. The car just continues to idle from the gas engine.

IMPORTANT POINT 2: I realize disconnecting the battery is probably just clearing the error lights. However, if there is a problem with a coolant pump, the inverter, or even the hybrid battery itself, disconnecting then reconnecting the 12v battery should not suddenly cure that problem. And by monkeying around with that 12v battery as I've described, the car works as designed and even switches back over to electric mode like it's supposed to. And keep in mind, I've seen no drop in MPG.

WHERE I AM TODAY: In a state of confusion & despair. A couple weeks ago, while hopped up on "Hopium", I installed a new 12V battey. The car worked like a champ for about a week and then the problem started again. The solution of disconnecting/reconnecting the 12v battery always cures it and power switches from the ICE to the HYBRID BATT just as it should.

CODES: After my latest "reset", I finally did what I should have done months ago. Went to the Auto Store and used their code reader. It shows one bone-chilling code which is permanent and un-eraseable: P0A80 "Replace Hybrid Battery Pack". But let's think about this folks. If the hybrid battery was bad, do you really think I would be getting consistently great MPG? (I'm wondering if this is simply a default error code based on high mileage)

WHAT I NEED: For anyone willing to help, I am looking for a logical sequence of tests and perhaps parts replacements from cheapest/most likely ... to most expensive. I figure working through such a series of steps will still be cheaper (and much more macho) than going to a dealer.

Hope someone out there can help me preserve my sanity... and my quickly-dwindling sense of manhood.

 

Currently near Plant City, Florida. Am I wrong to believe an OBD-2 scanner won't work?

 

Thanks, Sam. Yes, as I noted in my post, I realize what disconnecting the 12v battery does. However, do you really think disconnecting a 12V battery will suddenly make a bad hybrid battery functional again? Or a coolant pump? IMHO it doesn't make sense that a 12v disconnect/reconnect allows me to drive for several days with no issues. And, importantly, how can a bad hybrid battery be giving me 50+ MPG? These are the puzzling questions that haunt me.

You're definitely right though, regarding the complex nature of hybrid vehicles. Or cars in general for that matter. So, I can't just hit this thing with a hammer and make it work?

 

Thank you. I might look into that battery fan. Again, I'm just trying to apply a little common sense here and do an initial inspection of the most likely culprits. It does not make sense to me that a bad hybrid battery would consistently give me 51MPG. It charges just fine. No purple bar readings on this battery ever.

If the code scanner you recommended is reasonably priced, sounds like that would be a good thing to have.

 

Well, here's what I'm thinking.

Well, here's what I'm thinking. Since I had disconnected the battery, that could be why the codes were wiped. And perhaps since the "REPLACE HYBRID BATTERY PACK" code says "PERMANENT" , it can't be wiped. Thinking I should probably muster up the guts to drive this thing to autozone next time all codes are lit up but NOT reset the 12v battery first.

That might give me different scan results.

 

PLEASE NOTE: Thank you to everyone trying to help. It is my intention to get more accurate codes. However, I would rather not have this thread morph into a discussion of code scanners. Mostly looking for logical advice from someone who can make sense out of the circumstances I have described.

Also, please note that I have great respect for the many years of experience some of you have. But advice such as "you need to take it to a dealer" does not help me.

 

So... is this your way of suggesting I should test the hybrid battery? Or am I missing the nature of your recommendation.

 

Thank you. Maybe I need to shop around for a good diagnostic place. Because I'm pretty sure $75 won't even pay for a cup of coffee at my local dealer. What are your thoughts about simply scanning it myself with the appropriate tool?