SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule 13D

Under the Securities Exchange Act of 1934

(Amendment No. 4)*

Garrett Motion Inc.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

366505105

(CUSIP Number)

Attestor Limited

7 Seymour Street

London W1H 7JW, United Kingdom

Attention: Friedrich S. Andreae

Telephone: +44 (0) 20 7074 9610

with a copy to

Robert A. Profusek

Jones Day

250 Vesey Street

New York, New York 10281

(212) 326-3800

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

January 11, 2021

(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 that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ☐

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent.

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 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 366505105

Page 2 of 3 Pages

Explanatory Note

This Amendment No. 4 amends the statement on Schedule 13D filed with the Securities and Exchange Commission by Attestor Value Master Fund LP, Attestor Value Fund GP Limited, Attestor Capital Limited, Attestor Limited and Mr. Jan-Christoph Peters (collectively, the “Reporting Persons”) on October 27, 2020 (as amended, the “Schedule 13D”) with respect to shares of common stock, $0.001 par value per share (the “Shares”) of Garrett Motion Inc. (the “Company”). Capitalized terms used but not otherwise defined herein have the meanings set forth in the Schedule 13D.

On January 11, 2021, the Company entered into a Plan Support Agreement (including the term sheet attached thereto, the “Plan Support Agreement”) with the Equity Commitment Parties, Honeywell and the Consenting Noteholders (as defined therein), setting forth the terms by which the foregoing parties committed to provide capital to the Company in connection with its plan of reorganization. The Plan Support Agreement amended and restated the Third A&R Coordination Agreement, entered into by the Equity Commitment Parties, Honeywell and the Consenting Noteholders on December 22, 2020. The Plan Support Agreement is filed as Exhibit 99.1 hereto and incorporated by reference.

The Shareholder Parties by themselves or with the Equity Commitment Parties, Honeywell and the Consenting Noteholders (to the extent they own Shares) may be deemed to constitute a group for purposes of Rule 13d-3 under the Act. The Reporting Persons anticipate that the other Equity Commitment Parties, Honeywell and the Consenting Noteholders will file separate statements of beneficial ownership on Schedule 13D pursuant to Rule 13d-1(k)(2) under the Act, and any amendments thereto, containing their required information. The Reporting Persons assume no responsibility for the information contained in any filings by any other person. The Reporting Persons expressly disclaim beneficial ownership of any securities beneficially owned or acquired by any other person except to the extent of their pecuniary interest therein. As of the date of this Amendment No. 4, based on information provided by the other Equity Commitment Parties, Honeywell and the Consenting Noteholders, the Reporting Persons believe that the Equity Commitment Parties, Honeywell and the Consenting Noteholders beneficially own in the aggregate 57.6% of the 75,788,279 outstanding Shares, as reported in the Company’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 2, 2020.

The following documents are filed as exhibits to this statement:

CUSIP No. 366505105

Page 3 of 3 Pages

SIGNATURE

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

Dated: January 12, 2021

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