Boy, this system is confusing! I have an actuator AND a switchover valve for the EGR (aft of the air filter box), and another actuator (the larger unit with the black, round plastic top, in front of and just below the air filter box) and 2 switchover valves (near the radiator) for the "Boost Pressure Control" (wastegate?) and pressure control flap. I tried swapping the latter 2 switchover valves with each other a few days ago; no help.

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)