Description: Manifold Absolute Pressure Sensor. Fits STI, WRX Manifold Absolute Pressure Sensor A failed Manifold Absolute Pressure Sensor will often have no noticeable symptoms beyond a check engine light, but it does cause your Subaru to operate inefficiently and produce higher emissions. Our technicians have access to manufacturer-approved repair processes and Subaru genuine parts. WRX STI. Impreza. w/ turbo. From 08/21/2009.