Are you saying that you leave the key in over night and then have to remove it and reinsert it. If that is the case it is the way it works. If you leave the key in the off position to long it will require being reinserted.

Our ML with 52k on it (and same motor system), also does the start and die atleast once on cold mornings. I think it is slow to get up fuel pressure but I haven't verified it as it always starts and runs if one holds the gas down a little bit on the second try.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician