A car code scanner is a device that can read and display error codes stored by your vehicle’s computer. It can also reset the check engine light. There are a variety of scan tool models on the market, from basic to professional-grade. Some are plug-in modules that work with the onboard diagnostics (OBD) port, and others are wireless dongles that connect to your phone or computer. Some are even small enough to fit in your glove box. Before you buy a car code scanner, consider what you need it for.

All OBD2 (on-board diagnostics)-equipped vehicles since 1996 have a special port underneath the dash, beneath the steering wheel or sometimes in the ashtray. This is the OBD2 port and it allows a car code scanner to access your vehicle’s erro memory.

Some OBD2 scanners are dedicated to reading only engine-related fault codes that trigger the check engine light. The price range for these scanners is extremely wide, from very cheap to thousands of dollars depending on the depth of data they deliver.

Code Breaker Chronicles: The Role of Car Code Scanners in Automotive Care

Other OBD2 scanners allow you to read fault codes that pertain to all systems in the vehicle, not just engine-related ones. The last two digits of a code indicate which subsystem the code applies to, such as P0xxx codes are generic, or universal, while P1xxx codes are manufacturer-specific.

Most code readers have a simple interface that displays codes and their meanings, as well as clearing and resetting the check engine light. More advanced scan tools provide more in-depth data reading and playback, knowledge bases and diagnostic instructions, and built-in testing equipment like scopes and multimeters. Some have bidirectional communication capabilities and other special functions that are used by professional mechanics.