This happens about once a year, since I've owned the car and always resolves it's self after waiting a couple of minutes, just a price of admission?

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1999 E300 Turbodiesel 169,000 miles
1986 Porsche 944Turbo 20124 miles
1948 Dodge Deluxe 4 door 66521 miles

Had battery tested; it's fine.

No codes stored in system. So I'm not even sure how one would diagnose something like this anyway.

I guess all I can do at this point is maybe resolder the K40 cuz it's a good idea anyway and have my son keep two keys with him all times.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 158k miles
06 E320 CDI "Rutherford", Black on Tan, 177k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 72k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

This is not a DIY or even user freindly repair in any sense as it requires the proprietary MB software tool to interrogate and test.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

So do think that, even if MB couldn't reproduce the problem, they could accurately diagnose the issue? If it continues to happen, I wouldn't mind spending an hour's labor charge on knowing for certain.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 158k miles
06 E320 CDI "Rutherford", Black on Tan, 177k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 72k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife