A fault tolerant train door controller was developed based on cost effective embedded system. Based on the research of the faults occurring in a door control process it was concluded approach to fault detection and fault prevention from condition monitoring point of view. Using maintenance statistics the most common faults were isolated and their detection implemented within the designed controller. The controller functionality was described and supported by conducted experiments. Further analytical approach was shortly introduced and summarised work done showed that small embedded system can be a powerful fault diagnosis tool and condition monitoring system. Further improvements were proposed.