There are 3 pressure sensors on the Focus ST to measure intake and charge pressures. The first sensor is located on a plastic elbow which is bolted to the OEM airbox. This elbow is not changed with our intake kit, therefore not introducing heat from the aluminum tube to the Barometric pressure sensor that is attached.
The second sensor is located directly on the intercooler outlet before the final cold pipe heads into the throttle body. In factory form this is set in plastic as well and is subjected to excessive heat upwards of 185F due to the horrible cooling capacity of the factory core. If you are running the OEM intercooler, this sensor would be subject to the highest level of abuse and is likely to fail first of the three. Even while upgrading to our COBB intercooler, this sensor will end up being subjected to less heat over its lifespan than if it remained in the OEM unit.
The third sensor is located inside of the intake manifold, post throttle. While subjected to heat and pressure, this one has the benefit of the throttle blade to prevent constant abuse. I would suspect it to be the second in the line of failure prone pressure sensors of the 3, leaving the Barometric sensor being the last in line.