If you had health insurance all year that met minimum coverage requirements and selected in the Health Insurance section that you were covered all year, then the IRS should not require a Form 8965. They should have given you contact information in the notice, to make sure they have the right information.
This TurboTax FAQ has information on what coverage meets the Affordable Care Act minimum requirement for health insurance.
https://ttlc.intuit.com/replies/4263876
If you or someone on your return had insurance through the Marketplace, they might need a copy of Form 8962.
Turbo Tax can help you complete a Form 8962
if you have received a letter from the IRS asking for an update. Be sure to check if the letter references tax year 2017 or 2016. The form should have been generated when you entered your 1095-A into the Health Insurance section of Turbo Tax, but if for some reason it was not entered, these are the step-by-step instructions to add them.
https://ttlc.intuit.com/replies/6136902