Diagnostic Overview
Cummins fault code 268 generally points to fuel delivery, fuel pressure control, or injector-related performance. The ECM may detect that fuel pressure or fuel quantity is not responding correctly to engine demand. Common causes include plugged filters, weak fuel pump, pressure regulator failure, air intrusion, contaminated fuel, injector leakage, or a faulty pressure sensor. A technician should inspect fuel filters, verify fuel supply pressure, check for air in the fuel, review fuel pressure data, and check for related injector or rail pressure faults.