It is rare but not unusual to see warning in a vehicle's dashboard. Some of the faults can be diagnosed easily by observing the behaviour of the vehicle. For eaxmple, misfiring of the cylinders will result in unusual noises coming out of the engine. However, minor faults are often impossible to identify visually and diagnosis by qualified technician can reveal the exact status of the vehicle accurately. Most modern vehicles are equipped with a lot of sensors and analysing the data continuously can complement the visits to the garage so that any evolving trouble can be addressed immediately and avoid expensive repairs during periodic maintenance schedule.