As one example, a method of operating an engine system including a first air intake passage branch including a first compression device and a second air intake passage branch including a second compression device, wherein each of the first branch and the second branch are fluidly coupled to at least a combustion chamber the engine via a common intake passage, a first sensor arranged along the first branch and at least a second sensor arranged along the common intake passage, wherein the first sensor is a mass airflow sensor and wherein the second branch does not include a mass airflow sensor. The method comprises increasing the mass airflow through the first branch relative to the mass airflow through the second branch when an amount of decrease in the mass airflow through the first branch is more than half an amount of a corresponding decrease in the combined mass airflow.