EXHIBIT 23.1
CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
We consent to the reference to our firm under the caption "Experts" in the Registration Statement (Form S-3) and related Prospectus of Tocagen Inc. for the registration of common stock, preferred stock, debt securities and warrants and to the incorporation by reference therein of our report dated March 9, 2018, with respect to the financial statements of Tocagen Inc. included in its Annual Report (Form 10-K) for the year ended December 31, 2017, filed with the Securities and Exchange Commission.
/s/ Ernst & Young LLP
San Diego, California
May 11, 2018
