[DangWoo]

I've noticed an issue that has popped up on my 2014 228i (M-sport package, non-M-Sport brakes). While driving home today, I noticed the brake pedal has become very hard and it feels like I'm losing braking power to multiple wheels.

When it first started happening, the pedal was slightly firmer than normal, and the car was pulling to the right under braking. As I continued my trip home, the pedal became even harder and it feels like I'm no longer getting a brake boost and potentially only getting braking from the rear wheels.

Once home I turned off the car, pumped the brakes, and restarted. After restarting the pedal did not get any softer or depress any more than when the car was off.

I'm at a loss for what this could be, the car was functioning normally a day ago, and no work has been done on the car since then. I'm not sure where I should start looking (master cylinder, brake lines, calipers, brake booster, vacuum line, etc.). Any help would be greatly appreciated!

[HP Autosport]

You are on the right track. Check the brake booster and the vacuum line going to it.