Two days ago my Model S chimed and said car needs service notify TESLA. it did this on more than one occasion, so I took it to Tesla. no other message as to what the issue was. after a day and a half at the service center they couldn't find an issue, but here is the report. Concern: Customer: Alert appeared: Car Needs Service/Contact Tesla Service. 5/29 @ 3:48 PM Pay Type: Goodwill - Service Corrections: Vehicle Alerts General Diagnosis Pulled logs and reviewed withing time stamp given. Verified light illuminated for DCDC mia. Root causing this alert we found to be a power up timing issue with the module. Module was milliseconds delayed in powering up and other modules noticed it wasn't there thus triggering the alert on the screen. This is a rare bug that can happen but doesn't affect vehicle performance and there is no fix at this time. It is under investigation by engineering.