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.
273 fault codes documented· 7 engine variants · SPN / FMI / FC codes · 1998 - present
Most Common Cummins Fault Codes
Showing 24 of 273 Cummins codes, sorted by severity. Each links to causes, diagnostics, common fixes, and repair cost estimates.
CUMMINS-111 critical
ECM Critical Internal Failure
CUMMINS-115 critical
Engine Magnetic Speed/Position Lost Both of Two Signals
CUMMINS-143 critical
Oil Pressure Low - Warning
CUMMINS-151 critical
Engine Coolant Temperature High - Critical
CUMMINS-1663 critical
Aftertreatment 1 Diesel Oxidation Catalyst Missing
CUMMINS-1664 critical
Aftertreatment 1 Diesel Particulate Filter Missing
CUMMINS-1679 critical
Aftertreatment SCR Operator Inducement Severity
CUMMINS-217 critical
Engine Coolant Temperature High - Shutdown
CUMMINS-218 critical
Intake Manifold Temperature High - Shutdown
CUMMINS-219 critical
Engine Oil Pressure Extremely Low - Shutdown
CUMMINS-234 critical
Engine Crankshaft Speed/Position - Data Erratic (High)
CUMMINS-235 critical
Coolant Level Low - Critical
CUMMINS-254 critical
Fuel Shutoff Valve - Current Below Normal
CUMMINS-255 critical
Fuel Shutoff Valve - Current Above Normal
CUMMINS-259 critical
Fuel Shutoff Valve Stuck Open
CUMMINS-2641 critical
Aftertreatment SCR System - Fault Severity 1
CUMMINS-2642 critical
Aftertreatment SCR System - Fault Severity 2
CUMMINS-2643 critical
Aftertreatment SCR System - Final Inducement (5 mph limit)
CUMMINS-2648 critical
Aftertreatment SCR Efficiency - Data Valid But Below Normal Most Severe
CUMMINS-271 critical
Fuel Pump Pressurizing Actuator #1 Circuit - Voltage Below Normal
CUMMINS-272 critical
Fuel Pump Pressurizing Actuator #1 Circuit - Voltage Above Normal
CUMMINS-273 critical
Fuel Pump Pressurizing Actuator #1 Mechanical System Not Responding
CUMMINS-275 critical
Fuel Pump Pressurizing Actuator #2 Mechanical System Not Responding
CUMMINS-2778 critical
High Pressure Common Rail Fuel Pressure Relief Valve Stuck Open
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