The fault code is "P1570/Das enable not sent" and it will be stored in the engine control module. No warning/malfunction lights will come on. The key can't be re-programmed to correct a DAS problem. You should always have at least two working keys for a DAS equipped MB. Sometimes the keys can fail outright, and if you only have one you're stuck!!! Also, keep in mind that other DAS components can fail, not jusy keys.