My 17-year old son, who is my dependent, worked a part-time job in 2019. His earned income is less than $12,200. Does he need to file a tax return?

Not if he got a W-2 but check to see if he had any tax withheld that he can claim if he files.  If he does file be sure he checks the box saying he can be claimed by someone else. 

Your 17 year old dependent son does not need to file a tax return unless:

• His earned income (money you made by working) exceeds $12,200
• His unearned income (interest, dividends, capital gains, etc.) exceeds $1,100
• He had business or self-employment net income (gross minus expenses) or at least $400
• His gross income (earned plus unearned) exceeds the larger of $1,100 or his earned income (up to $11,850) plus $350

But even if his income falls below these filing requirements, he'll want to file a tax return to get a refund of any federal or state taxes withheld from his paychecks.