Detroit Diesel DD15 Fault Codes

Complete diagnostic trouble code reference for the Detroit Diesel DD15 heavy-duty diesel engine. 8 fault codes • Protocols: J1939

🔧 Engine Context: The Detroit DD series is the backbone of the Freightliner fleet. The DD15 is the 14.8-liter engine for long-haul operations, while the 12.8-liter DD13 serves regional applications. Both use Detroit's Amplified Common Rail (ACR) fuel system and BlueTec SCR aftertreatment. Common fault codes include ECM communication issues (SPN 625), SCR system malfunctions (SPN 520605), and DEF system failures.

SPN 625 FMI 9

ECM Communication Lost

Component: Engine Control Module / CAN Bus • J1939 SPN:625 FMI:9

🔴 STOP ENGINE

SPN 100 FMI 1

Engine Oil Pressure critically low

Component: Oil Pump / Oil Pressure Sensor • J1939 SPN:100 FMI:1

🔴 STOP ENGINE

SPN 110 FMI 15

Engine Coolant Temperature excessive

Component: Cooling System / Thermostat • J1939 SPN:110 FMI:15

🔴 STOP ENGINE

SPN 164 FMI 18

Fuel Rail Pressure critically low

Component: High Pressure Fuel System • J1939 SPN:164 FMI:18

🔴 STOP ENGINE

SPN 1761 FMI 18

DEF Tank Level critically low

Component: DEF Tank / DEF Level Sensor • J1939 SPN:1761 FMI:18

🟡 CHECK AT NEXT STOP

SPN 520605 FMI 7

SCR System Mechanical Malfunction

Component: SCR Catalyst / NOx Sensors • J1939 SPN:520605 FMI:7

🟡 CHECK AT NEXT STOP

SPN 597 FMI 7

Brake Pedal Position Switch

Component: Brake Pedal Position Switch / Air Brake System • J1939 SPN:597 FMI:7

🟡 CHECK AT NEXT STOP

SPN 84 FMI 19

Vehicle Speed Signal

Component: ABS Module / J1939 Data Link • J1939 SPN:84 FMI:19

🟠 CHECK SOON

Engine Series Coverage: Detroit Diesel DD15 engine specifications and fault codes sourced from SAE J1939/J1587 public standards and OEM technical service documentation. Last reviewed 2026-07-06T15:05:01Z.