To meet the increasing demand for potato chips in the Ethiopian market, potato processing businesses must enhance their overall equipment effectiveness and elevate their sigma level. Productive companies enhance OEE by minimizing downtime through root cause analysis, identifying issues systematically, and implementing proactive maintenance strategies for efficiency. As per the information provided by Senselet Food Processing PLC. In the annual production report, the company's overall equipment effectiveness fluctuated between 46% and 74%, with an average OEE of 64.5% in 2022. This study integrates the six-sigma DMAIC methodology with failure mode and effect analysis to enhance the productivity of the case company by improving the overall equipment effectiveness (OEE) and sigma level of the case company. Some published articles prove that a potential root cause with a higher RPN may or may not have a lower expected maintenance cost. This research identifies nine potential root causes, including issues such as lack of training, failure to read manuals, poor maintenance, improper machine storage, electrical problems, absence of scheduled maintenance, machine overruns, inadequate machine cleaning, and improper machine lubrication. The integration of DMAIC and FMEA occurs during the analysis phase, where the team quantifies potential root causes by assessing their occurrence, severity, and detection levels. To prioritize these causes, the risk priority number and the expected failure maintenance cost are calculated. Findings highlight that poor machine maintenance, and a lack of machine cleaning are the primary root causes, with expected costs of 1.5 and 0.9 million ETB, respectively. In terms of RPN, lack of machine cleaning and lack of scheduled maintenance rank highest. After implementing recommended actions, the packaging machine's OEE and sigma values improve from 4.70 to 5.70 and from 64.5% to 72.3%, respectively. The study strengthens the statement that a higher RPN does not necessarily correspond to a higher expected failure maintenance cost. Moreover, the crucial aspect of this research can be seen as the prioritization of root causes based on both RPN and expected maintenance costs for potential failures. Key Words: Six Sigma, DMAIC, FMEA, Overall Equipment Effectiveness.