Cummins Fault Code

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FC 441

ECM may lose communication; engine stumbles or display flickers.

System

Not specified

Symptom

ECM may lose communication; engine stumbles or display flickers.

Diagnosis & fix steps

ACTION: 1. Measure battery voltage (OFF: ~12.6V/25.2V). 2. Check Red power wires for corrosion at fuse link. 3. Clean all Black grounds.

Red Seal field insights

Check the battery disconnect switch. Over time, the internal contacts pit and create high resistance, dropping voltage only when the engine is under load.

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