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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-03-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001752104</rptOwnerCik>
            <rptOwnerName>Bracke Peter</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GARRETT MOTION INC.</rptOwnerStreet1>
            <rptOwnerStreet2>LA PIECE 16</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>Interim CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
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            <deemedExecutionDate></deemedExecutionDate>
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            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12050</value>
                </transactionShares>
                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
                    <value>A</value>
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                <sharesOwnedFollowingTransaction>
                    <value>64184</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
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                <transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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                </sharesOwnedFollowingTransaction>
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            <transactionTimeliness>
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            <transactionAmounts>
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                </transactionShares>
                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
                    <value>A</value>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>94083</value>
                </sharesOwnedFollowingTransaction>
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        <nonDerivativeTransaction>
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                <value>Common Stock</value>
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            <transactionDate>
                <value>2020-03-03</value>
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                <footnoteId id="F5"/>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
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                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
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        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
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            <transactionDate>
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            <deemedExecutionDate></deemedExecutionDate>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12050</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F1"/>
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            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>12050</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                    <value>0</value>
                </sharesOwnedFollowingTransaction>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
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            <conversionOrExercisePrice>
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            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
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            <transactionAmounts>
                <transactionShares>
                    <value>1598</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            <exerciseDate>
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            <expirationDate>
                <footnoteId id="F2"/>
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            <underlyingSecurity>
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                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1598</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                    <value>3196</value>
                </sharesOwnedFollowingTransaction>
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                <transactionCode>M</transactionCode>
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            <transactionTimeliness>
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                    <value>19907</value>
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                    <value>0</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
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                <value>Restricted Stock Units</value>
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            <conversionOrExercisePrice>
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                <value></value>
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                    <value>8394</value>
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                <transactionPricePerShare>
                    <value>0.00</value>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                    <value>Common Stock</value>
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                <sharesOwnedFollowingTransaction>
                    <value>8394</value>
                </sharesOwnedFollowingTransaction>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On October 1, 2018, the reporting person was granted 12,050 restricted stock units in connection with the conversion of certain equity and cash incentive awards previously granted by Honeywell International Inc. into equity awards of Garrett Motion Inc. in connection with the legal and structural separation of Garrett Motion Inc. (&quot;Garrett&quot;) from Honeywell International Inc. (such conversion, the &quot;Conversion&quot;). The restricted stock units vested in full on March 3, 2020.</footnote>
        <footnote id="F2">On October 1, 2018, in connection with the Conversion, the reporting person was granted 4,794 restricted stock units, which vested or will vest, as the case may be, in equal installments on March 3, 2020, February 27, 2021 and February 27, 2022, subject to continued employment.</footnote>
        <footnote id="F3">On October 1, 2018, in connection with the Conversion, the reporting person was granted 19,907 restricted stock units, which vested in full on March 3, 2020.</footnote>
        <footnote id="F4">On October 1, 2018, in connection with the Conversion, the reporting person was granted 16,788 restricted stock units, which vested or will vest, as the case may be, in equal installments on March 3, 2020 and February 28, 2021, subject to continued employment.</footnote>
        <footnote id="F5">Represents shares withheld by Garrett for payment of the tax liability incurred upon the partial or full vesting of the restricted stock units referenced in footnotes 1, 2, 3 and 4.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jerome Maironi, Attorney-in-Fact</signatureName>
        <signatureDate>2020-03-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
