A blowoff valve (BOV), dump valve or compressor bypass valve is a pressure release system present in most modern OEM road car applications. Its purpose is to prevent compressor surge / stalling and reduce wear on the turbocharger. These control valves remove the damaging impact of ‘surge loading’ by allowing the compressed air to vent away from the compressor wheel. This discharge can be heard as a distinct ‘dump valve’ hissing sound as it vents to atmosphere or back into the intake depending on the application and ECU airflow regulation. The Fiesta ST 1.6T Ecoboost uses an inexpensive electronic diverter valve as standard which is prone to failure and inconsistent results when used at higher boost pressure.