Comprehensive vehicle diagnostics can be carried out regularly, for preventive purposes, without special reasons, in order to check the condition of the vehicle and prevent breakdowns. It is imperative to subject the vehicle to comprehensive diagnostics if the vehicle behaves oddly, when buying a used car and after an accident, even if the damage seems to be minor. The comprehensive diagnostics comprises a visual inspection, a power train status check, a full inspection of the chassis and a comprehensive computer diagnostics. The visual inspection includes checking the condition of the body, interior, headlights and other light sources. The engine check is complex and starts from a general inspection of the engine to checking the compression in the cylinders, with the use of special tools and devices at this stage; the chassis is also subject to a thorough and comprehensive examination, including the brake system, shock absorbers, traction diagnostics, and so on; if necessary, the computer diagnostics is applied at all stages of the inspection and is used to check all electronic vehicle components. Moreover, the comprehensive diagnostics involves the verification of security systems and the serviceability of such options as an air conditioner, a heater and an infotainment system.