Hey folks, I got a 40% duty cycle fault on my 86 300E- 5 spd yesterday. I have had Hi idle, warm and cold @1400rpm since I got the car. My book says it a "Volume air flow sensor position indicator" fault-either between the CFI module or the sensor its self is bad. The question is 1) Has anyone ever had this fault? 2) The MB manual also usues the term Air flow sensor potentiameter (I know, same thing) but claims you need a Contact box . Does anyone know the proper way to test it? Volt/Ohm values? Thanks again. PS Is it true that once this is fixed, another fault with a higher duty cycle can be next?