Coliseum Capital Inches Up Stake In Universal Technical Institute Inc (UTI)

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No.     )*

UNIVERSAL
TECHNICAL INSTITUTE, INC.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

913915104

(CUSIP Number)

Christopher Shackelton/Adam Gray

Metro Center

1 Station
Place, 7th Floor South

Stamford, CT 06902

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

March 18, 2016

(Date of
Event Which Requires Filing of This Statement)

If the filing person has
previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of Sections 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following
box.  þ

The information required on the remainder of this cover page shall not be
deemed to be filed for the purpose of Section 18 of the Securities Exchange Act of 1934, as amended, (the Exchange Act) or otherwise subject to the liabilities of that section of the Exchange Act but shall be
subject to all other provisions of the Exchange Act (however, see the Notes).

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

This Schedule 13D (this Schedule 13D) supersedes the Schedule 13G as last amended by
Amendment No. 2 filed on January 11, 2016 with the Securities and Exchange Commission (the SEC) by Coliseum Capital Management, LLC (CCM), Coliseum Capital, LLC (CC), Coliseum
Capital Partners, L.P. (CCP), Coliseum Capital Partners II, L.P. (CCP2), Adam Gray (Gray) and Christopher Shackelton (Shackelton), relating to shares of common stock,
$0.0001 par value per share (the Common Stock), of Universal Technical Institute, Inc. (the Issuer), a corporation organized under the laws of Delaware. This Schedule 13D is being filed because the Reporting
Persons may no longer qualify to file on Schedule 13G. See Item 4 below.

This Schedule 13D relates to shares of the common stock, $0.0001 par value
per share, of Universal Technical Institute, Inc., a corporation organized under the laws of Delaware. The principal executive offices of the Issuer are located at 16220 North Scottsdale Road, Suite 100, Scottsdale, AZ 85254.

The persons filing this statement and the persons enumerated in Instruction C
of Schedule 13D and, where applicable, their respective places of organization, general partners, directors, executive officers and controlling persons and the information regarding them, are as follows:

The foregoing persons are hereinafter sometimes collectively referred to as the
Reporting Persons.

CCM is the investment adviser to CCP and CCP2, which are investment limited partnerships. CC is the General Partner of CCP
and CCP2. Gray and Shackelton are the managers of CC and CCM.

SCHEDULE 13D

The source and amount of funds used in purchasing
the Common Stock by the Reporting Persons and a separate account investment advisory client of CCM (the Separate Account) were as follows:

The Reporting Persons acquired the Common Stock for investment purposes, and
such purposes were made in the Reporting Persons ordinary course of business. In pursuing such investment purposes, the Reporting Persons may further purchase, hold, vote, trade, dispose or otherwise deal in the Common Stock at times, and in
such manner (including pursuant to hedging transactions), as they deem advisable to benefit from changes in market prices of the Common Stock, changes in the Issuers operations, business strategy or prospects, or from a sale or merger of the
Issuer. To evaluate such alternatives, the Reporting Persons routinely will monitor the Issuers operations, prospects, business development, management, competitive and strategic matters, capital structure, and prevailing market conditions, as
well as alternative investment opportunities, liquidity requirements of the Reporting Persons and other investment considerations. Consistent with their investment research methods and evaluation criteria, the Reporting Persons may discuss such
matters with management or directors of the Issuer, other shareholders, industry analysts, existing or potential strategic partners or competitors, investment and financing professionals, sources of credit and other investors. Such factors and
discussions may materially affect, and result in, the Reporting Persons modifying their ownership of the Common Stock, exchanging information with the Issuer pursuant to appropriate confidentiality or similar agreements, proposing changes in
the Issuers operations, governance or capitalization, or in proposing one or more of the other actions described in paragraphs (a) through (j) of Item 4 of Schedule 13D. The Reporting Persons reserve the right to formulate other
plans and/or make other proposals and take such actions with respect to their investment in the Issuer, including any or all of the actions set forth in paragraphs (a) through (j) of Item 4 of Schedule 13D, or acquire additional
Common Stock or dispose of all Common Stock beneficially owned by them, in public market or privately negotiated transactions. The Reporting Persons may at any time reconsider and change their plans or proposals relating to the foregoing.

SCHEDULE 13D

The information in Items 4 and 6 hereof is incorporated herein by reference.

CCM
is an investment adviser whose clients, including CCP, CCP2 and the Separate Account, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Common Stock. CC is the general partner of
CCP and CCP2. Gray and Shackelton are the managers of CC and CCM.

The Reporting Persons are parties to an agreement with respect to the joint filing of
this Schedule 13D and any amendments thereto. A copy of such agreement is attached as Exhibit 1 to this Schedule 13D and is incorporated by reference herein.

The information in Item 4 hereof is incorporated herein by reference.

SCHEDULE 13D

SIGNATURES

After reasonable inquiry and to the best of his or its knowledge and belief, each of the undersigned certifies that the information set forth in this
statement is true, complete and correct

DATED: March 21, 2016