Cummins is one of the most popular engines in today’s commercial trucks. With electronic engines, it should be no surprise that you often find yourself looking for repair information on a Cummins fault code. With our Diesel Repair platform, you’ll find that we have free repair information for every possible Cummins fault code that exists!

Cummins has had many different engines throughout the years and variations of the same model. For example, the Cummins ISX15 engine existed from 2010 model years through 2018. Depending on which year range, it could be a Cummins ISX15 CM2250 or a CM2350. The table below gives an overview of all the diesel-powered Cummins engines that has coverage on Diesel Repair for fault codes.

EngineEmissionsStart YearEnd YearNotes
C8.3 19851995 
C8.3E 19961997 
ISB5.9 19941998 
ISB5.9 19992003CM550
ISB6.7EPA1320132018CM2350 / B101
B6.7EPA1720172020CM2350 / B121B
B6.7EPA212021CurrentCM2450 / B155B
ISC 19982003CM554
ISL 20002003CM544
ISM 19992003CM570
ISX 19982000 
ISX 20012003CM570
L10 19821999 
M11CELECT Plus19951998 
N14CELECT Plus19952003 

Cummins Fault Codes Explained

Depending on which tool you use to retrieve fault codes from your Cummins engine, you may either see the generic SPN & FMI codes or the actual Cummins OEM fault code. You can use Diesel Repair to find information on these fault code both ways.

If you use a lower-quality tool or an electronic logging device (ELD), you will likely get an SPN, SID, and FMI fault code. Even the higher-end, dealer-level tools will display this information, but they will also show the actual OEM fault code.

Popular Cummins Fault Codes

To publish a list of every fault code would only do a little good, but we have published the most popular Cummins fault codes for some of their more recent engines. Inside Diesel Repair, you can find quick repair information for each of these codes for free, and paid members can enjoy our step-by-step repair directions to get fixed even more quickly.

Cummins X12

Below are the Top 10 fault codes for Cummins X12 CM2350, which is in the model year 2018, and newer commercial trucks. Codes 6254, 6255, & 3712 are all derated codes that occur when another fault is causing the actual problem. As you can see from the list, the diesel exhaust fluid (DEF) codes are the top 3 most common fault codes if you ignore the derate codes.

Fault CodeSPNFMIDescription
6254524616Aftertreatment SCR Operator Inducement
457230319Aftertreatment 1 Diesel Exhaust Fluid Tank Temperature
467717619Aftertreatment 1 Diesel Exhaust Fluid Tank Level
6255156915Engine Protection Torque Derate
386833649Aftertreatment Diesel Exhaust Fluid Quality
371252460Aftertreatment SCR Operator Inducement
55915718Injector Metering Rail 1 Pressure
6766325118Aftertreatment 1 Diesel Exhaust Fluid Property
3382305818Engine Exhaust Gas Recirculation (EGR) System
336110210Intake Manifold 1 Pressure

Cummins X12

This list includes the most popular fault codes for the Cummins X12 in 2022. The Cummins X12 has been used in commercial trucks from the model year 2018 to current.

Fault CodeSPNFMIDescription
6255156915Engine Protection Derate
3725321610Aftertreatment Intake Nox Sensor
192232510Aftertreatment Diesel Particulate Filter Pressure
457230319Aftertreatment 1 Diesel Exhaust Fluid Tank Temperature
111735972Power Supply Lost with Ignition On
386833649Aftertreatment Diesel Exhaust Fluid Quality
517767139Variable Geometry Turbocharger Actuator Software
371252460Aftertreatment SCR Operator Inducement
467717619Aftertreatment 1 Diesel Exhaust Fluid Tank Level
6254524616Aftertreatment SCR Operator Inducement Severity

Summary of Cummins Fault Codes

Cummins Fault Codes can be difficult to diagnose and repair, but we have you covered with Diesel Repair. Remember, the quick repair information is always free. Enhanced technical repair information can be purchased with subscriptions requiring no contracts and canceled at any time.