How do I read OBD-II codes?

You can read OBD-II codes using a scan tool or code reader plugged into the 16-pin OBD-II Data Link Connector (DLC) located under the dashboard. Affordable Bluetooth/WiFi adapters (like ELM327-based devices) can connect to smartphone apps such as Torque or OBD Fusion. Many auto parts stores like AutoZone and O'Reilly also offer free code reading services. Once connected, the scanner will display stored DTCs, pending codes, and freeze frame data.