It sounds like you may have accidentally indicated that you sold a vehicle during the vehicle portion of your interview. May I recommend that you review your vehicle entries? Here’s how to do this in TurboTax Online:

1. Under Income & Expenses (tab at the top of your screen), click Review next to Self-employment income and expenses.

    2. Click Review again next to the specific self-employed activity and scroll down to the Expenses category.

    3. Click Review next to the Vehicle section. Review all of your entries very closely.

I have the same problem. Using TurboTax Home & Business, one self-employed business, began the business in 2019. Used the car 95% for personal use, and only 5% for business use. Filing only for business mileage at standard rate and $8 of parking fees. Started using the vehicle for work 3/5/19. "I stopped using this vehicle in 2019" is NOT checked. 

Sorry; clicked Post too soon.  To continue: 

Yes, I own the vehicle. Yes, available for personal use. No, no other vehicle. Yes, tracked work miles. No, did not track personal miles. Total mileage, 10,000, business miles 831. Vehicles used 0-4. Standard mileage deduction. "Other expenses" is just the $8 parking fees. $490 vehicle deduction. That's everything for the vehicle. But when I do a Smark Check for federal taxes, it asks for depreciation allowed or allowable (I enter zero; too small to bother with), and then insists I give a date sold. How do I convince TurboTax I did NOT sell this vehicle? 

I'm not sure what happened, but I just posted exactly what you had.  Got the $490, and the depreciation form was properly calculated.

I would suggest that you go back to your

1. BUSINESS expenses
2. Business Vehicle Expense [UPDATE}
3. Now select [Delete]
4. Confirm the deletion
5. Post the vehicle again