S4 Quattro Cabriolet V8-4.2L (BHF) (2008)
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Vacuum Pump: Description and Operation
Electric Vacuum Pump
Only vehicles with automatic transmission are equipped with an electric vacuum pump. It is switched on by the Engine Control Module (ECM),
depending on intake manifold pressure.
The vacuum pump can be tested with On Board Diagnostic (OBD): any detected malfunctions are stored in the ECM.
The engine must not be running when checking the function of the electrical vacuum pump via (OBD).
