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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-02-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001743963</rptOwnerCik>
            <rptOwnerName>Maironi Jerome</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>LA PIECE 16</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ROLLE</rptOwnerCity>
            <rptOwnerState>V8</rptOwnerState>
            <rptOwnerZipCode>1180</rptOwnerZipCode>
            <rptOwnerStateDescription>SWITZERLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP, GC &amp; Corp. Secretary</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-02-28</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50038</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>293642</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The reported transaction involved the reporting person's receipt of a grant of restricted stock units (&quot;RSUs&quot;) under the 2018 Stock Incentive Plan of Garrett Motion Inc. and its Affiliates.  The RSUs are scheduled to vest in full on the third anniversary of the grant date, subject to continued employment.</footnote>
        <footnote id="F2">This information updates the information in the reporting person's previous Form 4 filed on March 6, 2019 (the &quot;Prior Form 4&quot;) to reflect the correct number of shares previously received from Honeywell International Inc. (&quot;Honeywell&quot;) as a pro rata dividend. On October 1, 2018, applicable Honeywell stockholders, including the reporting person, received one share of Garrett Motion Inc. (&quot;Garrett&quot;) common stock for every ten shares of Honeywell common stock held by such holder to effect the legal and structural separation of Garrett from Honeywell. On that date, the reporting person received a dividend from Honeywell in the aggregate amount of 670 shares of Garrett common stock.</footnote>
        <footnote id="F3">(continued from footnote 2) The Prior Form 4 inadvertently reported beneficial ownership of (a) an aggregate of 56,808 shares of Garrett common stock, rather than 57,239 shares actually beneficially owned as of that date, and (b) an aggregate amount of securities beneficially owned of 242,934 shares of Garrett common stock, rather than the aggregate of 243,604 shares of Garrett common stock actually beneficially owned as of that date. As of the date of filing of this Form 4, as reported in Column 5, the reporting person beneficially owns an aggregate of 293,642 shares of Garrett common stock, consisting of (a) 225,004 RSUs (inclusive of 50,038 newly-granted RSUs reported in Column 4) and (b) 68,638 shares of Garrett common stock (inclusive of the 670 shares described above).</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jerome Maironi</signatureName>
        <signatureDate>2020-03-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
