What is a Turbocharger Boost Pressure Solenoid?
Turbocharged engines use air pressure created by the turbocharger to force air into the engine through the intake manifold. The amount of pressure that even a small turbocharger makes can exceed the factory specifications for intake pressure, so a component to regulate the amount of pressure in the system is needed. To vent overpressure, the boost pressure control solenoid is used to open the wastegate on demand from the engine computer. This may be a solenoid and valve combination, or a solenoid that allows air into a vacuum canister to open the wastegate.
How do Turbocharger Boost Pressure Solenoids work?
The turbocharger boost pressure control solenoid is controlled by the engine management computer (ECM/PCM) and, depending on the manufacturer design, may open when the brakes are applied, the gas pedal is released, turbocharger speed becomes too low, or the boost pressure sensor detects overpressure. When the solenoid opens it allows the wastegate to open, sometimes indirectly, and boost pressure is vented into the exhaust pipe. Upon closing, the wastegate is pulled closed by the wastegate actuator, and the turbocharger will again build pressure in the system.
What are the symptoms of a bad Turbocharger Boost Pressure Solenoid?
If the boost pressure control solenoid fails to operate, the check engine light will illuminate, especially under hard or sustained acceleration. However, if the vehicle is always driven very lightly, it may never have a reason to actuate, but this depends on the software for the particular vehicle. The engine may feel more powerful than normal on hard acceleration, but the check engine light will stay illuminated, and the vehicle may set itself into limp mode or safe mode. Lean running conditions may be detected at high engine speed, and these symptoms will be noted by OBD-II trouble codes stored in the ECM.