For those that don’t know, the CP4 is the fuel injection pump that is installed on the second generation 3.0 TDIs. This injection pump uses only its fuel supply for lubrication, diesel first flows into the bottom end of the pump to lubricate the camshaft, rollers, lifters, and bushings before the diesel flows up to the metering valve to be used for injection. Unfortunately, the CP4 can be rather sensitive to fuel quality. If contamination occurs and one of the rollers gets stuck, the pump will start making metal shavings in the bottom end. As the CP4 continues to pump, it is now pumping diesel contaminated with metal shavings through the metering valve and into the rest of the injection system. When this failure occurs the CP4, injectors, fuel rails, rail pressure sensor, pressure control valve, high pressure lines, injector return lines, tank lines, and fuel module will all need to be replaced. This kit doesn’t prevent a failure from happening but it does isolate the CP4s lubrication supply from the injection fuel supply and prevents all the other components in the injection system from being damaged. Because of how the metering valve is isolated and given its own supply with this kit, now in the event of a failure only the CP4 and return filter will need to be replaced. This kit will fit 3.0 TDI equipped vehicles with the CPNB, CNRA, and CNRB engine codes. No tune is required for proper operation, also works with vehicles that have already been tuned. Please note intake manifold removal is required to install the kit, now is a good time to reseal anything in there if you deem necessary.