The Free Fault Code Search Tool from Pitstop | DTC Codes List

Free Fault Code Search Tool

Not all illuminated “check engine” lights on a truck are created equally! That’s why it’s critical to discover a fault code management solution that can help you interpret DTC and SPN fault code lists to diagnose your vehicle’s problem and know when the issue needs to be fixed. Use this free fault code search tool by Pitstop to quickly get a definition of the alert so you know if your maintenance shop can close out the fault code or act on it immediately.

Priority Descriptions:


Book an appointment right away with your mechanic.


Book an appointment in the coming weeks.


Often a “noisy” fault code that is likely fine until your next service visit.

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A Guide to Understanding Fault Codes

What is a fault code?

A fault code, also known as a diagnostic trouble code (DTC), is a unique code that is generated by a vehicle’s onboard diagnostic system (OBD) when there is an issue with one of the vehicle’s systems or components. The OBD system monitors various sensors and systems in the vehicle and will generate a fault code if it detects an issue.

What are the different types of fault codes?

There are two main types of fault codes: DTC and SPN. DTC codes are used in all vehicles and are standardized across all manufacturers. These codes are made up of five characters and are used to identify the specific system or component that is experiencing an issue. For example, a P0300 code indicates a random misfire detected in the engine.

On the other hand, SPN codes are specific to heavy-duty vehicles such as trucks and buses. These codes are longer than DTC codes and are used to identify the specific system, subsystem, or component that is experiencing an issue. For example, an SPN 520202 code might indicate an issue with the turbocharger on a heavy-duty diesel engine.

Where do fault codes come from?

Fault codes can come from various sources, including sensor issues, electrical systems, fuel systems, etc. When a fault code is generated, it is stored in the vehicle’s OBD system, which can be accessed by a mechanic or diagnostic tool to identify and diagnose the issue.

What are the most common fault codes? 

There are many different fault codes that can be generated by a vehicle’s onboard diagnostic system, and the specific codes that are most common can vary depending on the make and model of the vehicle. However, here are some examples of common fault codes that may be encountered.

It’s important to note that fault codes can be generated for many different reasons and that these codes are just a starting point for diagnosing issues with a vehicle. These fault codes can be diagnosed remotely using fleet maintenance software. However, a qualified mechanic will need to perform additional testing and inspections to determine the root cause of the problem and recommend the appropriate repairs.