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Q: The brake pedal goes all the way to the floorboard

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Two times in the same day the brake pedal went all the way to the floorboard. One of those times I was fortunately at a stop sign; the second time, I was at an almost-complete stop. This is so dangerous and I am scared to drive my SUV - what if it happened and resulted in an accident or injury. I have been to the dealership and I was told that the brakes are in proper working order and that they could not replicate the problem. They also told me that my 2013 model is equipped with an entirely different brake assembly than the prior years’ models, which had a verified brake-booster problem. From what I have observed, I am considering that there is a problem with the hydraulics in the master (booster) cylinder. In your professional experience, what do you think is causing the brake pedal to go all the way to the floorboard?

Hi. Your issue could very well be due to a faulty master cylinder. A fault in those particular model master cylinders have been experienced by QX56 owners in which air will seep into the brake fluid through the master cylinder. This is a difficult fault to find because the master cylinder is not electronically monitored. A trouble code will not develop for this component.

I suggest to have the braking system inspected by a certified technician. Be sure to inform them of the potential master cylinder fault. 

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