Hi Last November my brake booster AND accumulator failed at the same time. There were some hydraulic(?) noises for a while, which got worse over time, then one day a warning light came on and the brakes were hard, though the car was still able to stop. At that same exact time, there was an obvious reduction in acceleration and MPG. Prius was sluggish during acceleration and MPG dropped to 30-35 MPG. No codes for the battery. I fixed both brake problems, BUT the MPG and acceleration problems persisted. I replaced the 12v battery, but the problem still persisted. On a possibly related note, 4-5 months later the head gasket goes. My theory is the engine was working harder than it should have and eventually a HG issue formed. No one has been able to confirm or even entertain this idea. I'm thinking about fixing the HG or replacing the motor. But won't if there is a deeper hybrid system issue. Does this sound like a battery or hybrid issue for anyone else?
I’m no expert on the Gen 1 Prius Plug-in by a long shot, but could the problem be related to the regenerative braking system? Reduce regenerative braking and you reduce fuel efficiency. Your problem started with the brakes, so maybe the repair wasn’t complete. Just my initial thoughts (and again, I not that knowledgeable about your car).
around 210K Not sure about the range. I never really charge it since I was traveling for work. I'm having my guy look.
