Ford Focus III (2011-2021) check engine light diagrams & schemes

On-board Diagnostics (OBD-II) for check engine light

Your Ford's On-board Diagnostics (OBD-II) system has a data port for diagnostics, repair, and reprogramming services with diagnostic scan tools. Installing a non-Ford-approved aftermarket OBD plug-in device that uses the port during normal driving, for example, remote insurance company monitoring, remote vehicle diagnostics, telematics or engine reprogramming may cause interference or damage to vehicle systems. We do not recommend or endorse the use of any non-Ford-approved aftermarket OBD plug-in devices. The vehicle Warranty may not cover damage caused by any non-Ford-approved aftermarket OBD plug-in device.

If the service engine soon indicator light stays illuminated after you start the engine, it indicates that the On Board Diagnostics system (OBD) has detected a malfunction of the vehicle emissions control system. Refer to On board diagnostics (OBD) in the Fuel and Refueling chapter for more information about having your vehicle serviced. See Emission Control System

Check engine light is blinking

If the light is blinking, engine misfire is occurring which could damage your catalytic converter. Drive in a moderate fashion (avoid heavy acceleration and deceleration) and have your vehicle serviced immediately.

The service engine soon indicator light illuminates when you first switch the ignition on before engine start to check the bulb and to indicate whether the vehicle is ready for Inspection/Maintenance (I/M) testing.

Normally, the service engine soon light stays on until you crank the engine, then turns itself off if no malfunctions are present. However, if after 15 seconds the service engine soon light blinks eight times, it means that the vehicle is not ready for I/M testing

The check engine light indicates an error that was detected by Engine Control Unit (ECU). All modern cars, including Ford Focus, have a check engine control. The check engine light does not have to mean a serious fault. However, it is worth diagnosing the problem as soon as possible. If switching Ford Focus on and off does not turn off the check engine light, you must diagnose the problem. To check what causes the problem, you should scan the engine computer. For this purpose, the OBD II connector is used, to which we connect a diagnostic scanner or a diagnostic interface and a computer with appropriate software. When the check light stays on, it's best to see a mechanic. If Ford Focus is put into service mode (maximum speed and revs are limited), visit the mechanic as soon as possible.