The industry standard for most heavy-duty trucks and buses Most diesel engine manufactured vehicles or equipment are J1939 compliant Is your vehicle OBD-II or J1939 compliant?Ĭars and light trucks built and sold in the United States after Januwere required to be OBD-II equipped. Manufacturers may create their own DTCs to supplement the list of universal codes if the vehicle requires it, but more often than not these manufacturer-specific codes are difficult to interpret without a mechanic. Though OBD-II is widely used, it is important to note that manufacturer-specific DTCs still exist. With the implementation of OBD-II, a standard DTC list that contains codes that are common to all manufacturers was created by the Society of Automotive Engineers (SAE). J1939 - best for heavy-duty vehicles and heavy equipment OBD2 - best for light- and medium-duty vehicles Today, there are two main standards that people can use to read DTCs. Over the years, several different versions of OBD interfaces were used-these interfaces, now classified as OBD-I, largely varied from manufacturer to manufacturer. It is also what allows external devices, such as an OBD scanner, to interact with a vehicle’s onboard computer system. The OBD both diagnoses the fault and displays the DTC through visible warnings such as the illumination of a check engine light.

Where do DTCs come from?ĭTCs are generated by the vehicle’s on-board diagnostics (OBD) system whenever a fault is detected.

Read on to learn more about DTCs, how they work, and how you can read them. Having a basic understanding of DTCs can be helpful for drivers and fleet managers. DTCs are also called engine vehicle fault codes codes, and can be read with a scanner that plugs directly into the port of a vehicle. While the malfunction indicator lamp (MIL)-also known as the check engine light-simply alerts drivers that there is an issue, a DTC identifies what and where the issue is. A DTC, short for Diagnostic Trouble Code, is a code used to diagnose malfunctions in a vehicle or heavy equipment.

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