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Bosch-Common Rail System – Boost pressure control solenoid valve

Function

The boost pressure control solenoid valve is supplied with vacuum by the vacuum pump. Pulse width modulated signals from the PCM control this vacuum via the boost pressure control solenoid valve. The controlled vacuum acts upon the vacuum unit of the turbocharger.

Effects of faults

In the event of a fault, boost pressure control is no longer possible. Due to this, the injected fuel quantity is limited (power output reduction) and the EGR system is switched off.

Diagnosis

Boost pressure control operates in a closed control loop. The adjustment of the guide vanes of the variable geometry turbocharger is carried out via the boost pressure control solenoid valve. The boost pressure is controlled depending on requirements via the MAP sensor.

Faults on the boost pressure control solenoid valve or on the vacuum system are detected by the MAP sensor. As the EGR system is deactivated, the NOX emissions increase sharply. As a result, EOBD limits are exceeded. Therefore this is a MIL active component.

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