Won T Start — Possible Fault Codes

Found 4 fault codes associated with won t start. Codes are sorted by severity — check STOP ENGINE codes first.

⚠️ 2 STOP ENGINE-level codes associated with this symptom. Do not continue driving.

SPN 625 FMI 9

ECM Communication Lost

Detroit Diesel DD15 • Component: Engine Control Module / CAN Bus • J1939

🔴 STOP ENGINE

SPN 1077 FMI 14

High Pressure Fuel Rail Pressure

PACCAR MX-13 • Component: High Pressure Fuel Pump / Rail • J1939

🔴 STOP ENGINE

MID 128 SID 1 FMI 5

Injector Cylinder 1 Circuit

Cummins ISX15 • Component: Fuel Injector #1 Solenoid Circuit • J1587

🟡 CHECK AT NEXT STOP

SPN 647 FMI 4

Engine Speed Sensor

PACCAR MX-13 • Component: Crankshaft Position Sensor (CKP) • J1939

🟡 CHECK AT NEXT STOP

⚠️ Diagnostic Note: Symptoms can have multiple root causes. Always verify with a diagnostic scan tool before replacing parts. The fault codes listed above are possible matches for won t start based on SAE J1939/J1587 fault code definitions and OEM service documentation.