A method (50) for isolating a fault within an engine system (10) including an engine control module (40) and a diagnostics module (36) includes determining, by the engine control module (40), a plurality of parameters of the engine system (10), calculating a likelihood of the fault using a log-likelihood ratio analysis of data within the engine control module (40), and providing a plurality of fault determinations and the likelihood of each of the plurality of fault determinations using plurality of parameters and the diagnostics module (36) of the engine system (10).