Pressure Regulator Valve 4009956 – Compatible with Cummins ISX15 / QSX15 Engines. High-quality pressure regulator valve designed to maintain optimal fuel system pressure and ensure efficient engine performance. Suitable for Cummins ISX15 and QSX15 engines, this valve helps improve fuel efficiency, engine reliability, and overall performance. Part Number: 4009956,4009956cum, 180153,4009957. Application: Cummins ISX15, QSX15 engines CM870 CM871 CM871E. Condition: New / Replacement Part. Function: Regulates fuel pressure for smooth engine operation. Quality: Durable construction, tested for reliability. Direct fit replacement. Stable and accurate pressure control. Improves engine efficiency. Long service life.