Diagnostic Trouble Codes

What Are Diagnostic Trouble Codes?

Modern vehicles have internal computers that not only control the overall performance of your car, truck or SUV, but they also alert you to a problem by generating trouble codes. Of course, if your vehicle’s computer produces one, you need to know what your trouble code means.

Before exploring what each code means and how to fix it, you should understand two important concepts.

  • The on-board computer diagnostic system is the integrated tool that monitors many of your vehicle’s essential systems. The OBD may alert you to problems with your vehicle’s engine, airbags, antilock brakes and other components. Since 1996, vehicles have an OBD-II diagnostic system. If your vehicle has this system, you need an OBD-II diagnostic scanner to communicate with its OBD system.
  • The diagnostic trouble code is the code your OBD generates to tell you something is wrong. Reading as a series of five letters and numbers, the DTC allows you to home in on the system that is not functioning properly. For example, if your vehicle’s OBD detects a leak in the evaporative emission system, you may see a P0442 code. On most vehicles nowadays, there are hundreds of possible DTCs a car can generate.

The error detected may be dependent on what different makes of vehicles are capable of generating. That is, you may see a certain code on an OBD-II system for your BMW, Chevrolet, Chrysler, Dodge, Ford, GMC, Jeep, Subaru, Toyota or another type of vehicle. Additionally, while an OBD code is not necessarily specific to a certain make or model of vehicle, the steps required to remedy it likely depend on the type of car, truck or SUV you drive.

You can get to the bottom of your vehicle’s diagnostics by purchasing your own code reader, or you can bring your car to your local AutoZone and get it scanned as a part of our free Fix Finder service.