EXHIBIT31.2                

|   | 1. | I      have reviewed this Quarterly Report on Form 10-Q of Ridgewood Energy Y      Fund, LLC; |
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|   | 2. | Based      on my knowledge, this report does not contain any untrue statement of a      material fact or omit to state a material fact necessary to make the      statements made, in light of the circumstances under which such statements      were made, not misleading with respect to the period covered by this      report; |
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|   | 3. | Based      on my knowledge, the financial statements, and other financial information      included in this report, fairly present in all material respects the      financial condition, results of operations and cash flows of the      registrant as of, and for, the periods presented in this      report; |
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|   | 4. | The      registrant’s other certifying officer(s) and I are responsible for      establishing and maintaining disclosure controls and procedures (as      defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal      control over financial reporting (as defined in Exchange Act Rule s 13a –      15(f) and 15d – 15(f))  for the registrant and    have: |
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|   | 5. | The      registrant’s other certifying officer(s) and I have disclosed, based on      our most recent evaluation of internal control over financial reporting,      to the registrant’s auditors and the audit committee of the registrant’s      board of directors (or persons performing the equivalent      functions): |
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| Dated:     |   | May      21, 2009                                                                 |
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|                           |   |                                                                              |
| /s/                            |   | KATHLEEN      P. MCSHERRY                                                         |
| Name:                          |   | Kathleen      P. McSherry                                                         |
|                           |   |                                                                              |
| Title:                         |   | Executive      Vice President and Chief Financial Officer     |
|                           |   | (Principal      FinancialOfficer)                                                 |

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