As Gilly said.

I had an 03 in that the SBC unit had "timed out". You have to hook it up to SDS to determine if this has happened. If it has and the car is still under 10 years old MB will replace the unit at no charge. Not sure why they set it up this way. Nice that they will replace it at no charge though.

Not sure you are going to be able to tell much using the AutoZone type scanner.

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Jim