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.

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.

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.

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.