FORM 6-K SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 Report of Foreign Private Issuer Pursuant to Rule 13a - 16 or 15d - 16 of the Securities Exchange Act of 1934 For the month of: October, 2023 Commission File Number: 1-12384 SUNCOR ENERGY INC. (Name of registrant) 150 – 6th Avenue S.W. P.O. Box 2844 Calgary, Alberta Canada, T2P 3E3 Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F: Form 20-F ¨ Form 40-F x Indicate by check m ...