An engine diagnostic fault code check is a specially designed test that can detect fault codes submitted by your vehicle’s Electronic Control Unit (ECU). Your car has several sensors that are connected to the ‘brain’ of your vehicle, these sensors give the car signals if there is an issue. These signals are usually in the form of dashboard warning lights. However, fault codes can be detected if there is a noticeable mechanical issue. This test can provide a mechanic with the general area a problem is occurring, pointing them in the right direction for investigation and repair.