Hello All, A have a 2008 Prius new to me. It makes a clicking sound from seemingly on top of the gas tank. at first I thought it had something to do with the gas tank (I have had to replace 2 of my 2009 prius gas tanks). However, I eventually noticed that the clicking sounds occur at key near car before ignition on, when sitting stopped with brake pressed, and after ignition off for up to several minutes. I have replaced about six actuators and this isn't that. Eventually after several weeks of driving it produced a C1391 loss of pressure code. When I cleared it with techstream the clicking sounds got a lot quieter but still there. It almost seems as if there is some sort of brake pressure relief valve on top of or near the gas tank but I have no idea if this is even a thing. Help. An no this isn't actuator noise from up front. I have the back panels and seats removed as I had to replace the hybrid battery after purchase land can hear the noise seemingly on top of the gas tank. I would thing some sort of evaporative purge noise from something failing (which would have been annoying as I discarded the old tanks after replacement). It is clearly linked to brake pedal pressure when stopped as at a light. No sound during mnormal driving. And lifting foot to barely stopping does lessen or stop the sound.
I'm drawing a blank on your noise. "brake pressure relief valve" isn't a thing. But I did notice you spelled C1391 with a P. If you still have the Edit button available for your post, you can fix that, and then it won't be a distraction to other readers (and searches will group it correctly with other posts about the same code).
Maybe bleed the rear brakes relay stay in person sits in the car hold the pedal down the pump does the work I bet there's some air back there on the passenger side rear.
Yes, got the letter wrong. I had a hard time finding out how to even post the thread. No edit button that I see. It was in fact a C1391. Edit button here naturally :}
