Hello, My wife's 1997 C280 MIL has come on with code P0170 only. The car has 150K miles on it and we are the original owners. I went for a ride and logged the long term fuel trim with the MIL on 1.32% and off 1.32% A few days later the MIL came on again. I have searched this forum as well as the internet for a troubleshooting procedure specifically for the AMM. What is the common mode of failure for the AMM, is it a wide open condition or a drift outside of the normal operating range? There should be an acceptable range of resistance values or frequencies at a given RPM/Load/Temp/Humidity for this device. Does anyone have the pinout descrition for the connector? In a second note I have seen the AMM for this car range in price from $169(Ebay, manufactured in the same plant as the MB but not labeled MB) to $474 (dealer, definetly labeled MB), has anyone bought one from ebay with good results? Thanks for your help!