The ISX15 CM2250 and CM2350 has eliminated the injector camshaft due to the advent of the common rail fuel system in which the fuel is pressurized from a high pressure, multiple piston pump, transferred through tubing to a rail where fuel is stored under extremely high pressures up to 35,000 psi. DEF is heated, pumped and injected into a decomposition tube which then reacts with the exhaust reducing NOX. SCR consists of a Diesel Exhaust Fluid (DEF - composed of urea and water) injection system: holding tank, pump, controller, and injector and an SCR catalyst brick. The current EPA 2010 version known as ISX15 CM2250 features enhanced Exhaust Gas Recirculation, Diesel Particulate Filter and Selective Catalytic Reduction (SCR), also known as Urea Injection.

In motorhomes this was available as a 600 or 650 HP version.

With the help of the Diesel Oxidation Catalyst (DOC) the soot trapped in the DPF is oxidized and turned to ash during a process called regeneration. In 2008, Cummins unveiled the ISX CM871, this engine featured a Diesel Particulate Filter (DPF) which trapped the particulate matter or 'soot' produced in the engine. In 2002, the ISX CM870 brought cooled exhaust gas recirculation (EGR) which takes exhaust gas and recirculates it back into the intake of the engine lowering the combustion chamber temperatures limiting the formation of NOx. It has a one piece valve cover that is either plastic or on older models a chrome plated steel cover otherwise known as the Signature 600 or ISX CM570. The fuel system uses an Integrated Fuel System Module (IFSM) with a lift pump, gear pump, pressure regulators, shutoff valve, metering and timing actuators to deliver fuel to the injectors. This injection system is known as HPI (high pressure injection) where the injectors are cam-actuated to create injection pressure. Until 2010 this engine was a dual overhead cam design with one cam actuating the injectors and the other the valve train.

2015 cummins injectors