Use OBD-II scan applications to diagnose a car. All cars manufactured since 1996 have OBD-II systems to which drivers can connect scan tools. The car sends OBD-II error codes to the tool, which then sends the codes to an application. The driver can then use the application to expand a scan code to see the cause of a problem with the vehicle.
Although rare, it is possible for a car to display a false OBD-II code, meaning that the car may misinterpret the data it receives from sensors. If you are absolutely certain that the component indicated by the OBD-II application is not faulty, you can delete the code from the car's memory. If the car does not display the code again, the code was likely a false one. However, if you see the code again, double check the component, and take the vehicle to a mechanic if necessary.
You can use a wireless OBD-II reader and install an ODB-II application to your smartphone to perform diagnostics practically anywhere. One such tool, OBDLink MX Wi-Fi Scan Tool, reads the engine in real time and warns the user via the mobile application when there's a problem. The manufacturer claims that the tool is compatible with all cars that display OBD-II codes and that it has protection against hacking attempts.