Cummins Fault Codes
Cummins Inc. has powered on-highway diesel trucks, pickups, and commercial equipment since 1919. This hub covers fault codes, SPN/FMI pairs, and Cummins-specific fault code (FC) lookups for the ISB, ISC, ISL, ISM, ISX, and X15 engine families. From the legendary 5.9L 24-valve in Dodge Ram pickups to the 15-liter X15 powering the majority of Class 8 semis in North America.
7 engine variants · SPN / FMI / FC codes · 1998 - present
Cummins Engine Versions
| Engine | Years | Applications | Notes |
|---|---|---|---|
| ISB 5.9L | 1998-2007 | Dodge Ram 2500/3500 | Legendary 24-valve; HPCR from 2003. Bulletproof with proper maintenance. |
| ISB 6.7L | 2007-present | Ram 2500/3500, Ram HD Chassis Cab | Current medium-duty pickup engine. DPF, SCR (2013+), variable geometry turbo. |
| ISC 8.3L | 1998-2010 | Medium-duty trucks, RV, fire trucks | Inline-6 medium-duty platform. Replaced by ISL 8.9L. |
| ISL 8.9L / ISL9 | 2002-present | Class 6-7 trucks, motorcoach, RV | Medium/heavy duty applications. Popular in bus and RV chassis. |
| ISM 10.8L | 1998-2010 | Class 8 vocational trucks | Older heavy-duty platform; largely replaced by ISX15. |
| ISX 15L | 2001-2009 | Class 8 semis, on-highway | Pre-SCR big bore. Early EGR-only emissions strategy. |
| ISX15 / X15 | 2010-present | Class 8 on-highway, vocational | SCR + DPF + EGR. Efficiency Series and Performance Series variants. Most common Class 8 engine in North America. |
Common Cummins Issues
- EGR cooler failures, especially on ISX pre-2010 engines
- DEF doser and DEF quality sensor faults on 2010+ ISX15 / X15 and ISB 6.7L
- DPF regeneration issues and derate conditions (inducement levels 1-4)
- Turbo actuator (VGT) faults -- sticking vanes and position sensor issues
- High-pressure fuel pump wear and injector leak-off problems on ISB 6.7L
- NOx sensor (inlet and outlet) failures triggering SCR efficiency codes
Most Common Fault Codes
Cummins fault code data is being imported. Individual code pages with SPN/FMI descriptions, diagnostic flowcharts, and real-world fixes are coming soon. In the meantime, you can browse the existing diesel code database.