<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-11-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001735707</issuerCik>
        <issuerName>Garrett Motion Inc.</issuerName>
        <issuerTradingSymbol>GTX/GTXMQ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000773840</rptOwnerCik>
            <rptOwnerName>HONEYWELL INTERNATIONAL INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>300 SOUTH TRYON STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>May be a member of 10% group</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-11-13</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>17100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.18</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2877116</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents the weighted average price of the shares sold. The prices of the shares sold pursuant to the transaction ranged from $4.16 to $4.18 per share. The Reporting Person, upon request, will provide the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares sold at each separate price.</footnote>
    </footnotes>

    <remarks>The Reporting Person may be deemed to be a member of a group (for purposes of Rule 13d-3 under the Securities Exchange Act of 1934) with certain shareholders of Garrett Motion Inc. party to the Second Amended and Restated Coordination Agreement, dated November 2, 2020, as further amended, filed as Exhibit 99.1 to the Reporting Person's Schedule 13D/A filed on November 3, 2020, as amended. The Reporting Person disclaims beneficial ownership of any securities reported by any other person except to the extent of its pecuniary interest therein.</remarks>

    <ownerSignature>
        <signatureName>/s/ Anne T. Madden, Senior Vice President and General Counsel of Honeywell International Inc.</signatureName>
        <signatureDate>2020-11-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
