All modern cars contain on-board computers that monitor and/or control such things like emissions levels, engine temperature and even windscreen wipers. If something goes wrong within these systems, these computers produce fault codes which can only be read by a vehicle diagnostics equipment.
Your car will display an Engine Management Light on the dashboard to indicate there is a problem that needs to be investigated. The fault codes we read with our diagnostic equipment will give an idea of what area of the car has a problem, our trained Technicians are then able to investigate and trace the fault to identify the exact cause of the problem and establish what is required to complete the repair.
This is what some Engine Management Lights look like on your dashboard -