Physically Unclonable Functions (PUFs) are emerging cryptographic primitives used to implement low-cost device authentication and secure secret key generation. Several solutions exists for classical CMOS devices/the most investigated solutions today for weak PUF implementation are based on the use of SRAMs which offer the advantage of reusing the memories that already exist in many designs. The high reliability of SRAM-PUFs achieved today by using Fuzzy extractor structures combined with complex error correcting codes (ECCs) which increase the complexity and cost of the design. In this paper we define an effective method to identify the unreliable cells in the PUF implementation based on SRAM stability test. This information is used to significantly reduce the need for complex ECCs resulting in efficient, low cost PUF implementations.