Crewed space missions involve substantial risks, making the reliability of critical systems essential for ensuring crew safety. The Cabin Pressure Control System (CPCS) is a key system responsible for maintaining the partial pressure of oxygen within specified limits in the crew module. Given the critical role of the CPCS in manned space missions, a simulator has been developed to demonstrate the proof of concept of its design. This simulator will undergo initial testing on the ground before being deployed in precursor unmanned missions. As the design concept is being validated, it is crucial to assess the residual risk in the CPCS simulator, identify potential failure pathways, quantify the associated risks, and make risk-informed decisions regarding possible design alternatives. This paper aims to provide an in-depth analysis of these risk evaluation processes to enhance the reliability of the CPCS in future crewed space missions. A comprehensive fault tree analysis has been conducted to examine various failure modes of the Cabin Pressure Control System (CPCS) and their potential impacts. An uncertainty analysis was also performed to account for variations in failure rates and probabilities. To further refine the risk assessment, a minimal cut set analysis was utilized to identify the most critical failure paths within the system, while an influence analysis was employed to determine the most sensitive components towards the overall system reliability. These analytical methods collectively provide a deeper understanding of the CPCS’s reliability and highlight key areas for improving system safety and performance.