Diagnostic Overview
Cummins fault code 1844 commonly relates to EGR system flow, EGR valve response, or air-handling performance. The ECM may command EGR flow but not see the expected change in pressure, temperature, or airflow. Causes include a sticking EGR valve, plugged EGR cooler, carbon buildup in EGR passages, failed EGR differential pressure sensor, plugged sensor tubes, intake leaks, exhaust leaks, or wiring issues. Diagnosis should compare commanded versus actual EGR operation and inspect the EGR valve, cooler, pressure sensor tubes, and intake tract.