A vehicle braking system includes a brake pedal, master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator. A pedal feel simulator is coupled to the master cylinder output side through a switchable valve, the pedal feel simulator providing a reaction force. An isolation valve closes to isolate the braking circuit from the master cylinder and the simulator circuit. A primary pressure sensor generates a braking request signal responsive to the brake pedal. A controller activates the brake pressure generator to apply a braking force to the wheel cylinder based on the braking request signal. The controller identifies an abnormal value from the primary pressure sensor and couples the pedal feel simulator with a secondary pressure sensor within the braking circuit to determine whether the abnormal value indicates a primary pressure sensor malfunction or a malfunction of the pedal feel simulator or the switchable simulator valve.