If your vehicle is throwing a check engine light, but you don't have a diagnostic scanner handy, here are three tricks to try before seeing a mechanic.

Reading OBD codes requires an OBD scanner, which can cost between $30 and $60. It’s a handheld tool with a 16-pin trapezoidal connector that plugs into the vehicle and interprets the OBD code.

A scanner plugs into this connector. GM designed these pre-OBD-II systems to allow mechanics to read trouble codes without a scan tool.