A diagnostic procedure is presented purposely for the turbocharging system of 1 MW internal combustion engine (I.C.E.) and specifically, for the filters and compressor modules. This study is part of a wider research activity, concerning the development of a diagnosis system dedicated to the cogenerative I.C.E. installed at the Engineering Faculty in Perugia. Firstly a 1-D thermodynamic model of the CHP engine working fluid was developed to simulate failure conditions of the turbocharging groups, which are not directly replicable on the I.C.E. to avoid plant stoppage. This model is able to simulate the degradation in performance of the engine components. It also takes into account the effect of compensation which the regulation system activates in case of efficiency loss or failure relative to filters or compressors. In order to identify and assess such failures, the fuzzy logic was chosen as the tool for the diagnosis system design. The developed diagnosis system displayed a good reliability degree with the 1-D thermodynamic model results, for operating conditions in correspondence of bad performance either on behalf of the filters or the compressor. Moreover, the procedure can be implemented in the plant monitoring system and provides in real-time diagnosis results about the status of the components and the need of maintenance, on the basis of few parameters already measured on the I.C.E. (C) 2013 Elsevier Ltd. All rights reserved.