S54 CPV KitA common problem on the S54 engines, the Constant Pressure Valve O ring fails causing a slow oil leak on the passenger side of the engine that frequently resembles a rear main seal leak. Replacing the CPV with our included upgraded Viton O ring ensures a long term solution to this common problem. Our CPV Kit includes a brand new constant pressure valve and the special tool needed to access the valve behind the exhaust header. Without the tool,