My 07 ML350 did the same thing for an improperly tightened gas cap. A quick call to the dealership, and I was told it would take a few engine start/stop cycles before the CE indicator would go away. It took a couple of days before it did finally disappear.

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car