PT. XYZ is a part of the largest oil and Gas Company in Indonesia, responsible for managing and developing oil and gas production activities in the East Java. The Central Processing Area serves as the facility for processing fluids produced from the East Java fields. The processed output consists of three phases: Gas, Oil, and Water. The operation of the Gas Engine G102-B TBG620 V16K running 24 hours a day to generate electricity at the central processing area of PT. XYZ requires regular maintenance, including scheduled preventive maintenance and unplanned or corrective maintenance. In the event of troubleshooting, such as a decrease in temperature in chamber 2B or a temperature sensor reading of 280 °C in that chamber, immediate corrective maintenance is necessary. Based on observations conducted in the power plant area, two possibilities causing the temperature decrease in that chamber were identified. The first possibility was the need for spark plug replacement, and the second was a malfunctioning temperature sensor resulting in incorrect readings. Therefore, the spark plug replacement was performed first, requiring a gas engine shutdown for approximately 2 hours for repairs. After the spark plug replacement, it was discovered that there was no change in the temperature reading in chamber 2B, which remained at 280 °C. Hence, the corrective maintenance performed did not have a significant impact because the issue was caused by a faulty temperature sensor. However, it was observed that there was a 1.16% increase in the generated power compared to before the corrective maintenance was conducted. The difference in power output could be attributed to variations in the quality of gas used in the combustion process of the gas engine.