UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A10-K

For the fiscal year ended December 31, 2014.2015.

OR

For the transition period from                    to                     .

Commission file number of the issuing entity: 333-170231-14333-194765-06

CIK number of the issuing entity: 0001657146

AMERICREDIT AUTOMOBILE RECEIVABLES TRUST 2013-52015-4

(Exact name of issuing entity as specified in its charter)

Commission File Number of depositor: 333-170231333-194765

CIK number of depositor: 0001347185

AFS SENSUB CORP.

(Exact name of depositor as specified in its charter)

Commission File Number of sponsor: 001-13329

CIK number of sponsor: 0001002761

AMERICREDIT FINANCIAL SERVICES, INC.

(Exact name of sponsor as specified in its charter)

Registrant’s telephone number, including area code (817) 302-7000

Securities Registered Pursuant to Section 12 (b) of the Securities Exchange Act of 1934: None

Securities Registered Pursuant to Section 12 (g) of the Securities Exchange Act of 1934: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

    Yes  ¨    No  x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

    Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15 (d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

    Yes  ¨x    No  ¨

Indicate by check mark if the disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§229.405 of this chapter) is not contained herein and will not be contained, to the best of the registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.    x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer or a smaller reporting company. See definition of “accelerated filer and large accelerated filer” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).     Yes  ¨    No  x

State the aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day of the registrant’s most recently completed second fiscal quarter.

Not applicable to this registrant

List hereunder the following documents if incorporated by reference and the part of the Form 10-K (e.g. Part I, Part II, etc.) into which the document is incorporated: (1) Any annual report to security holders; (2) Any proxy information statement; and (3) Any prospectus filed pursuant to Rule 424(b) or (c) under the Securities Act of 1933. The listed documents should be clearly described for identification purposes (e.g., annual report to security holders for fiscal year ended December 24, 1980).

None.

Explanatory Note:

The Form 10-K for the issuing entity’s fiscal year ended December 31, 2014 was originally filed on March 31, 2015. This Form 10-K/A is being filed to correct an error in the Section 302 Certification and to correct an error in Management’s Assertion attached to the Form 10-K as Exhibits 31.1 and 33.1. A corrected and updated Section 302 Certification and Management’s Assertion are attached to this Form 10-K/A as Exhibits 31.1 and 33.1.

Except for the updated exhibits described above, this Form 10-K/A does not update, modify or amend any other information or any other exhibits as originally filed on the Form 10-K. Therefore, this Form 10-K/A does not reflect events occurring after the original filing date of the Form 10-K and does not update those disclosures as affected by subsequent events. Accordingly, this Form 10-K/A should be read in conjunction with the Form 10-K and with other filings made by the issuing entity with the Securities and Exchange Commission subsequent to the filing of the Form 10-K.

PART I

The following Items have been omitted in accordance with General Instruction J to Form 10-K:10-K:

None.

ITEM 1B. UNRESOLVED STAFF COMMENTSNot Applicable.

None.

PART II

The following Items have been omitted in accordance with General Instruction J to Form 10-K:

None.

PART III

The following Items have been omitted in accordance with General Instruction J to Form 10-K:

ITEM 9B. OTHER INFORMATION

None.

PART III

The following Items have been omitted in accordance with General Instruction J to Form 10-K:

SUBSTITUTE INFORMATION INCLUDED IN ACCORDANCE WITH GENERAL INSTRUCTION J TO

FORM 10-K:

ITEM 1112(b) OF REGULATION AB. (SIGNIFICANT OBLIGORS OF POOL ASSETS)

There is no single obligor that represents more than 10% of the pool assets.

ITEM 1114(b)(2) OF REGULATION AB. (CREDIT ENHANCEMENT AND OTHER SUPPORT, EXCEPT FOR CERTAIN DERIVATIVES INSTRUMENTS (FINANCIAL INFORMATION))

There is no external credit enhancement or other support provider that is liable to provide payments supporting any notes or certificates issued by the Issuing Entity.

ITEM 1115(b) OF REGULATION AB. (CERTAIN DERIVATIVE INFORMATION (FINANCIAL INFORMATION))

No entity provides any derivative instruments that are used to alter the payment characteristics of the cash flows from the Issuing Entity.

ITEM 1117 OF REGULATION AB. (LEGAL PROCEEDINGS)

As a consumer finance company, the sponsor is subject to various consumer claims and litigation seeking damages and statutory penalties, based upon, among other things, usury, disclosure inaccuracies, wrongful repossession, violations of bankruptcy stay provisions, certificate of title disputes, fraud, breach of contract and discriminatory treatment of credit applicants. Some litigation against the sponsor could take the form of class action complaints by consumers and certain legal actions include claims for substantial compensatory and/or punitive damages or claims for indeterminate amounts of damages.

In July 2014, in connection with an investigation by the U.S. Department of Justice in contemplation of a civil proceeding for potential violations of the Financial Institutions Reform, Recovery, and Enforcement Act of 1989, General Motors Financial Company, Inc. (“General Motors Financial”), immediate parent of the sponsor, was served with a subpoena by the U.S. Department of Justice directing it to produce certain documents relating to its and its subsidiaries’ and affiliates’ origination and securitization of subprime automobile loans since 2007. Among other matters, the subpoena requests information relating to the underwriting criteria used to originate these automobile loans and the representations and warranties relating to those underwriting criteria that were made in connection with the securitization of the automobile loans. General Motors Financial has subsequently been served with additional investigative subpoenas to produce documents from state attorneys general and other governmental offices relating to its retail auto loan business and securitization of auto loans. In October 2014, General Motors Financial received a document request from the Securities and Exchange Commission in connection with its investigation into certain practices in subprime auto loan securitization. These investigations are ongoing and could in the future result in the imposition of damages, fines or civil or criminal claims and/or penalties.

No assurance can be given that the ultimate outcome of the investigations or any resulting proceedings would not materially and adversely affect General Motors Financial or any of its subsidiaries and affiliates, including the servicer, or the interests of the noteholders or the servicer’s ability to perform its duties under the transaction documents. In the ordinary course of business, The Bank of New York Mellon is named as a defendant in or made a party to pending and potential legal actions. In connection with its role as trustee of certain residential mortgage-backed securitization, or RMBS, transactions, The Bank of New York Mellon has been named as a defendant in a number of legal actions brought by RMBS investors. These lawsuits allege that the trustee had expansive duties under the governing agreements, including the duty to investigate and pursue breach of representation and warranty claims against other parties to the RMBS transactions. While it is inherently difficult to predict the eventual outcomes of pending actions, The Bank of New York Mellon denies liability and intends to defend the litigations vigorously.

ITEM 1119 OF REGULATION AB. (AFFILIATIONS AND CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS)

Information required by Item 1119 of Regulation AB has been omitted from this report on Form 10-K in reliance on the Instruction to Item 1119.

ITEM 1122 OF REGULATION AB. COMPLIANCE WITH APPLICABLE SERVICING CRITERIA.

The following documents are filed as part of this report.

The Servicer has complied, in all material respects, with the Applicable Servicing Criteria.

ITEM 1123 OF REGULATION AB, SERVICER COMPLIANCE STATEMENT

The following documents are filed as part of this report.

SIGNATURES

Pursuant to the requirements of Section 13 or 15 (d) of the Securities Exchange Act of 1934, AFS SenSub Corp. has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Supplemental information to be Furnished With Reports Filed Pursuant to Section 15(d) of the Act by Registrants Which Have Not Registered Securities Pursuant to Section 12 of the Act.

No annual report, proxy statement, form of proxy or other proxy soliciting material has been sent to certificateholders, and the registrant does not presently contemplate sending any such materials subsequent to the filing of this report.

EXHIBIT INDEX

AMERICREDIT AUTOMOBILE RECEIVABLES TRUST 2015-4

ITEM 15 EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

(a)(1) Not Applicable

(a)(2) Not Applicable

(a)(3) As reported under clause (b)

SUBSTITUTE INFORMATION INCLUDED IN ACCORDANCE WITH GENERAL INSTRUCTION J TOFORM 10-K:

ITEM 1112(b) OF REGULATION AB. (SIGNIFICANT OBLIGORS OF POOL ASSETS)

There is no single obligor that represents more than 10% of the pool assets.

ITEM 1114(b)(2) OF REGULATION AB. (CREDIT ENHANCEMENT AND OTHER SUPPORT, EXCEPT FOR CERTAIN DERIVATIVES INSTRUMENTS (FINANCIAL INFORMATION))

There is no external credit enhancement or other support provider that is liable to provide payments supporting any notes or certificates issued by the Issuing Entity.

ITEM 1115(b) OF REGULATION AB. (CERTAIN DERIVATIVE INFORMATION (FINANCIAL INFORMATION))

No entity provides any derivative instruments that are used to alter the payment characteristics of the cash flows from the Issuing Entity.

ITEM 1117 OF REGULATION AB. (LEGAL PROCEEDINGS)

General Motors Financial Company, Inc. (the “Company”), the ultimate parent of the registrant, has been served with investigative subpoenas to produce documents from state attorneys general and other governmental offices relating to its sub-prime auto finance business and securitization of subprime auto loans. In addition, the Company received a document request from the Securities and Exchange Commission in connection with its investigation into certain practices in subprime auto loan securitization. The Company is investigating these matters internally and believes the Company is cooperating with all requests. Such investigations could in the future result in the imposition of damages, fines or civil or criminal claims and/or penalties.

On November 24, 2014, a group of investors filed a civil complaint against multiple trustees in the United States District Court for the Southern District of New York, purportedly on behalf of and for the benefit of certain residential mortgage backed securities (RMBS) trusts. These filings assert claims for alleged failure by the trustees to enforce repurchase obligations of mortgage loan sellers for purported breaches of representations and warranties, to notify investors of alleged events of default purportedly caused by breaches by mortgage loan servicers and failure to abide by appropriate standards of care following alleged events of default.

ITEM 1119 OF REGULATION AB. (AFFILIATIONS AND CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS)

AmeriCredit Financial Services Inc., the Sponsor and the servicer, is a Delaware corporation and is the originator of 100% of the automobile loan contracts. The Sponsor purchases automobile loan contracts that are originated and assigned to it by automobile dealers and, to a lesser extent, third-party lenders and also originates automobile loan contracts directly with consumers, either directly or through a wholly-owned subsidiary. The Sponsor services all automobile loan contracts that it purchases or originates on behalf of the Issuing Entity, AmeriCredit Automobile Receivables Trust 2013-5, a Delaware statutory trust.

The Sponsor sold and assigned the pool of initial automobile loan contracts to AFS SenSub Corp., the Depositor, a Nevada corporation. The Depositor then sold the pool of sub-prime automobile loan contracts to the Issuing Entity and is the sole owner of the certificate of the Issuing Entity.

General Motors Financial of Canada, Ltd., orGMF of Canada, is a wholly-owned subsidiary of the Sponsor. GMF of Canada services a portion of the automobile loan contracts in the United States on behalf of the Issuing Entity through its service center in Peterborough, Ontario. GMF of Canada utilizes the Sponsor’s standardized servicing policies and procedures and operates on the same single, unified and interconnected software platform that the Sponsor’s other servicing centers utilize. GMF of Canada is managed by the same executive officers of the Sponsor that oversee the rest of the Sponsor’s operations, including servicing through its other servicing centers. GMF of Canada is operated as a separate legal entity from the Sponsor due solely to the location of its servicing center in a foreign jurisdiction, despite being operated identically to the Sponsor’s other servicing centers and not as a stand-alone entity (other than as is required for regulatory and corporate governance purposes).

ITEM 1122 OF REGULATION AB. COMPLIANCE WITH APPLICABLE SERVICING CRITERIA.

The following documents are filed as part of this report.

The Servicer has complied, in all material respects, with the Applicable Servicing Criteria.

ITEM 1123 OF REGULATION AB, SERVICER COMPLIANCE STATEMENT

The following documents are filed as part of this report.

SIGNATURES

Pursuant to the requirements of Section 13 or 15 (d) of the Securities Exchange Act of 1934, AFS SenSub Corp. has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Supplemental information to be Furnished With Reports Filed Pursuant to Section 15(d) of the Act by Registrants Which Have Not Registered Securities Pursuant to Section 12 of the Act.

No annual report, proxy statement, form of proxy or other proxy soliciting material has been sent to certificateholders, and the registrant does not presently contemplate sending any such materials subsequent to the filing of this report.

EXHIBIT INDEX

AMERICREDIT AUTOMOBILE RECEIVABLES TRUST 2013-5