A method for testing a fuel cell stack includes providing a fluid, such as an ammonia-containing fluid, in a first reactant flow path in a first portion of the fuel cell stack, detecting the presence of the fluid using a detector, such as an ammonia detector, positioned within or adjacent to a second portion of the fuel cell stack that is separated from the first portion of the fuel cell stack and determining the presence of a defect in the stack based on detecting the presence of the fluid. Further embodiments relate to testing a fuel cell stack using a microphone that detects an audio signal indicative of a stack defect.