CarParts.com (PRTS) 10-Q 2007 Q1 Quarterly report

EXHIBIT 32.2

CERTIFICATION PURSUANT TO

18 U.S.C. §1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of U.S. Auto Parts Network, Inc. (the “Company”) on Form 10-Q for the quarter ended March 31, 2007 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Michael J. McClane, Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 15, 2007

/s/ MICHAEL J. McCLANE

Michael J. McClane

Chief Financial Officer

A signed original of this written statement required by Section 906, or any other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.