C 240 4MATIC Wagon (203.281) V6-2.6L (112.916) (2003)
The aspirator shutoff valve (126) is opened via the air pump switchover valve through vacuum or closed through ventilation. The injected air of the air
pump can flow through if the aspirator shutoff valve is actuated.
The check valve (126b) prevents when air injection is deactivated the flowing in of exhaust to the vacuum diaphragm (126a) and therefore protects it
against thermal destruction and contamination.