Does anyone know what the the official Toyota procedure is for testing the traction battery pack, and what the criteria is for initiating such a test ?
I ask because one of my prius's is starting to become less efficient - that is the average MPG is has 22 k miles on it, and the driving conditions have not changed. I suspect the traction battery is failing.

I dont trust the dealers, so before I take it in, I am gathering information.