Car is a 98 E300D. What is an ERG valve, and what causes it to get clogged. Can running the engine with it clogged cause any damage? And, generally, how often does it clog and have to be replaced? Thank you....RSL007

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RSL007
1999 ML430
2001 C320 Sport
2000 SAAB 9-5
1998 E300DT
1998 C280sport
1991 300D
1991 350SDL
1982 300DT
1972 Porsche 911 Targa