Hybrid battery problem or just its cooling fan?

You need to first get us the trouble codes it's throwing; because it's obviously intermittent. The trouble codes will tell you what the ECU doesn't like, because right now your just guessing. The OEM clearly states to keep those vents clear, just because your doing that now, doesn't mean that you haven't already damaged the traction pack. This is like, not doing an oil change until the oil lamp lights up. Is the AC working and do you use it? Set the HVAC to auto and 70 degrees to see if the problem reoccurs.

 

Dr. Prius is more than enough to catch the specific error code. Once you pull that data through the scanner, it'll be pretty obvious what's actually triggering the warning.

 

a prius aware scanner should give you more detailed codes. look into autel maxi 200. idk if it will work with the c or not.
dr prius will give you module voltages. it might be worth opening up the battery and looking for corrosion

 

A good scanner is the right start to troubleshooting.

It's easy to say that a 2015 should be due for replacement about now; that's a pretty normal expectation. But maybe not. A report from a good prius-aware scanner should help.

Good luck!

 

A P0A80 is enough for Toyota to replace the hybrid battery if it is still under warranty. It does not mean its too hot because those are separate codes. It means the modules are unevenly worn which reduces capacity for the whole assembly.

If they were too hot the controllers would speed up the fan. Dr Prius can increase fan speed but it goes back to controller logic the minute you don't have Dr Prius connected and in the foreground.

So called "rebuilders" use data Techstream or low cost bluetooth apps like Dr Prius or Car Scanner have as a starting point to teardown and test individual modules with custom loads, chargers and voltmeters. Modules that are bad are replaced with better used modules. It can take weeks to do it right at home with minimal tool investment. Even then, the user may have to teardown and replace more bad modules yearly.

Or they buy "rebuilt" assemblies with "warranties" but still play wack a mole with poor reliability unlike the first ten or fifteen years.

Bus bar corrosion can be a problem and good "rebuilders" will replace them.

Want "forget about it" reliability for your wife? I know I do. Which is why I bought a new oem pack years ago.

 

Perhaps better than just using Dr Prius to get an error code - might be to use Dr Prius to record a log file as you do a nice long drive.

On varied roads, up and down hills and at slow an high speed. Then email yourself the resulting log which you can easily upload as a file to an AI - I've used both Grok and chatGPT - which will give you a detailed, and expert report on the condition of the pack and any problems it may have. As a relative novice at this sort of thing, I found this very useful and very educational!

Even if you are not in a position to service the pack yourself, it should give you enough insight to judge whether or not to believe a diagnosis you may subsequently get from a 'pro' ? Also, try uploading to more than one AI, as they vary in the style of their reports and one might be better or more easiiy interpreted than another! A print-out might also be a good guide for anyone who does look at the pack for you.

 

Got to be kidding...