Master Warning, Check Engine, and Brake Warning Lights

Certainly looks like a hybrid battery issue.
If Hybrid Battery is not working properly, the regenerative braking system is unable to put energy back into the hybrid battery. So the brakes feel different.

Start gathering your money for a replacement.

 

clean the cooling fan, 12v looks weak too. how many miles on her?

 

I'm not saying it isn't the traction battery. It may be going out. But, as @bisco said, 12.0 volts on the aux battery is pretty low with no load and that can give you all sorts of codes.

 

no way to know. it does seem like the hybrid, but low voltage to the computers can wreak havoc. if you are saying that you don't want to replace the 12v, because if it's the hybrid battery, you're going to dump it, i understand.

 

if you're going to keep the car, and 12 volts is an accurate cold measurement, you'll be replacing the 12v anyway. any idea how old it is?

 

Load test your 12v battery....measure of voltage is not the way you should check your battery health

Posted via the PriusChat mobile app.

 

I have read that as a preventative thing, you should replace the 12V battery every 4-5 years. Older 12V batteries can throw codes at you that might not be true.

 

This is very subjective and should be taken with a grain of salt, and very much depends on the operating environment and how well the battery has been maintained. I find it hard to throw out a perfectly serviceable battery just because some arbitrary time limit has passed. Test the battery and if it is not up to snuff, replace it.

It is not really that they are not true, and it is not until you look at what caused the code to come up, you probably find one of the things the computer is not happy about is the low voltage on the 12 V supply.