Diesel Engine Fault Code Reference
Browse fault code references for all major diesel engine platforms. Each guide covers the top 30 SPN/FMI fault codes with symptoms, causes, and step-by-step diagnostic procedures.
Cummins X15 / ISX15
The most common heavy-duty diesel engine in North America. Covers ISX15 and X15 Efficiency/Performance Series.
Displacement15.0L
Power400–605 HP
ApplicationsPeterbilt, Kenworth, Freightliner
30 fault codes covered →
Detroit DD15
The flagship Detroit Diesel engine for Freightliner Cascadia trucks. Requires DDDL for full diagnostics.
Displacement14.8L
Power455–560 HP
ApplicationsFreightliner Cascadia, Western Star
30 fault codes covered →
PACCAR MX-13
PACCAR's proprietary engine for Kenworth and Peterbilt trucks. Shares architecture with DAF engines.
Displacement12.9L
Power405–510 HP
ApplicationsKenworth T680/T880, Peterbilt 579/389
30 fault codes covered →
Don't See Your Engine?
The AI Diesel Tech knowledge base covers fault codes for all J1939-compliant diesel engines. Search by SPN/FMI code or start an AI diagnostic session for any engine platform.