Pennsylvania Statutes Title 42 Pa.C.S.A. Judiciary and Judicial Procedure § 5525. Four year limitation

(1) An action upon a contract, under seal or otherwise, for the sale, construction or furnishing of tangible personal property or fixtures.

(2) Any action subject to 13 Pa.C.S. § 2725 (relating to statute of limitations in contracts for sale).

(3) An action upon an express contract not founded upon an instrument in writing.

(4) An action upon a contract implied in law, except an action subject to another limitation specified in this subchapter.

(5) An action upon a judgment or decree of any court of the United States or of any state.

(6) An action upon any official bond of a public official, officer or employee.

(7) An action upon a negotiable or nonnegotiable bond, note or other similar instrument in writing. Where such an instrument is payable upon demand, the time within which an action on it must be commenced shall be computed from the later of either demand or any payment of principal of or interest on the instrument.

(8) An action upon a contract, obligation or liability founded upon a writing not specified in paragraph (7), under seal or otherwise, except an action subject to another limitation specified in this subchapter.