Focus ST225 OEM Boost Control Solenoid
This is an original (O.E.M) Ford part made by Pierburg for the Focus ST225.
The boost control solenoid on the Ford Focus ST225 is located behind the turbo and is responsible for controling the turbo actuator through the variang stages of commanded boost.
The solenoid itself is manufactured by Pierburg and is found to be a very reliable and maintenance free component, however if you are experiencing problems with your commanded boost or any lumpiness when coming on or off the throttle this may be the culprit and certainly worth changing, especially on vehicles running heavy mods.
We have found from performing diagnostics on hundreds of these cars over the years that there are 3 common sensors which tend to be responsible for the majority of poor running issues and lack of power and even esp system faults. These would be
Mass AirFlow sensor > MAF
Manifold Absolute Pressure Sensor > MAP
Boost Control Solenoid.
These 3 sensors all communicate with each other, the MAF first records and reports the characteristics of the air passing through it, the boost solenoid commands a set boost and the MAP sensor then calculates what boost pressure should be received after the turbo in the charge system. We do recommend on vehicles which are 3 years old or older that have never changed these sensors to do so to restore your vehicles lost performance, smoothness and responsiveness it would by now have lost.
We do offer a sensor pack which includes all 3 sensors.
*all recommendations are from vehicle observation and are not irrefutable to solving faults, these are simply guidelines*