From where did the PO source the MAF? The reason I ask is that quality varies greatly. I first bought a cheapie off eBay, and it failed within 2 weeks. The seller graciously allowed an exchange, but the exchanged part failed within a month. I finally broke down and paid $250 from FastLane and haven't had any issues since. I was getting the CEL with the cheap eBay MAFs. Do you have the ability to swap MAF with a known good one?

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280