Mine started to clunk when I press the brake pedal. The only recent thing to occur was a panic stop, so not sure if that triggered it. The car has 125k on it. Does this mean the brake actuator is failing or is it a normal Prius thing?
If you don't know your brakes enough to open them up and take a look, take it to a brake shop for inspection. The actuator failure will generate diagnostic test codes and produce the rattling sound under the hood. Noises while braking are not a normal thing for any car. Brakes are critical safety equipment--don't ignore any change or any noise. It's over ten years old--get it looked at! It could be a suspension issue, which is also critical since that's what keeps the wheels attached to the car. Any brake shop can diagnose those issues as well.
+1.....except I would avoid the dealer with this issue, since mysterious brake noises produce the same reaction from their service techs as my shaking a container of dog food does with our dog.
