If my eyes don’t deceive me as to which valve that is...

Here’s information on the pressure switch that triggers the valve - https://www.pelicanparts.com/techarticles/Mercedes-W123/22-ELEC-Boost_Sensor_Replacement/22-ELEC-Boost_Sensor_Replacement.htm

Confirm the valve by following one plastic line to a banjo bolt at the tail end of the intake manifold, and the other line to a banjo bolt on the ALDA atop the IP.

Then confirm the signal by checking continuity between the switch and one pin in the valve connector. The other pin should get constant 12V with the key on, engine running or not.

Back to the switch, check for continuity between the single electrical post and ground. It should be an open circuit until the setpoint of 0.85 bar or whatever spec is. If it’s a continuously open circuit longer than the typical valve clicking frequency, maybe the wire between the pressure switch and valve is grounding somewhere.

If the switch is sending a periodic ground signal with the engine off, spray some brake parts cleaner into the open end of the pressure switch then see if the periodic ground signal persists.

Again, I don’t see how this valve can affect the transmission. It’s not part of the vacuum system.

Sixto
98 E320s sedan and wagon
02 C320 wagon