Five problems related to brake master cylinder have been reported for the 2012 Toyota Prius. The most recently reported issues are listed below.
Brake master cylinder and brake booster failed and needed to be replaced.
While driving the brakes went out. I brought the car to Toyota and they said the brake booster is defective and needs to be replaced the price to do so is about $3,000 they also said they don't know why this happened as in some cases you never have to replace a brake booster nor master cylinder.
11/15/19 originally the car showed brake, abs, antiskid and engine idiot lights went to the dealer with a code c1391. They said I need to replace the master cylinder and the power booster for $2600. Then they said it was policy to also replace the brake booster pump assembly for an additional $2,000 or a total of $4600. After I complained that they had recalled 972,000 other Prius but didn't include the Prius v they said I only needed to replace the master cylinder and power booster and said they would do it for $1,516. 89. So then I go to take the car to the service department today 12/4/19 and while sitting there the idiot lights all turn off and the brake start to function normally own its own. . . I ask the service representative what his thoughts were and he said I should still make the repairs, but he couldn't say what they would do it came back. So I'm going to drive the car for a week to see. While I'm waiting can you please do a recall on the brake pump assemebly since these folks dont even know what the heck is going on with this car. It appears its not either device and its a computer glitch that they haven't resolved. . . Help us Prius owners please!!!.
My car has the same brake booster/master cylinder defect that the 2010/11 model Prius were recalled for. Brake booster or brake pressure accumulator failure on 2012 models causes loss of braking effectiveness. Serious safety issue that can cause death. Toyota is well aware of this. This happens in motion at highway speeds.
Car was in motion and brake pedal went half way to floor and abs, brake, traction control and tire sensor lights came on. Master cylinder or brake booster seem to have failed. Dealer didn't recognize codes and could only recommend changing spark plugs when I just had them replace 6-8 months prior. Explained that did think that had anything to do with brakes giving out. They reset codes and sure enough happened again within the next 30 days. Toyota admitted to since receiving many reports of certain internal malfunctions of brake booster assemblies. 4 trips later to dealer the response is the codes are not coming up (dtcs) c1391, c1252, c1256 or c1253 in order to be covered it's voluntary customer support program which has brake booster and brake booster pump coverage. Very frustrating!.