The commonest cause for electrical faults in cars is the 'short circuit' which typically is caused by the so-called 'clashes' in the wiring system. Unless you are professionally qualified in the field of auto vehicle wiring (or mechantronics), you are advised against attempting to carry out auto electrical repairs on faults emanating from 'short circuits.' Getting things wrong here could, in the worst case scenario, see your car up in fire!
With other electrically powered features, the cause (and the fix) may not be so simple. Because of that, if any electric accessory stops working it's a good idea to first check whether a fuse that protects the circuit it's on has blown. The owners manual should show where a fuse for a particular feature is located (usually in a side panel below the dashboard near the driver's seat or under the hood). If you're handy with a multimeter that measures voltage, resistance and other things, you may be able to diagnose some of your own electrical problems. However, because they can be difficult for professionals to find and fix, they might be even harder for amateur technicians to solve.
Engine analyzer - This vehicle diagnostic tool is absolutely essential in any car repair shop. It is used to test important aspects of any engine like primary and secondary ignition timing, carburetor integrity, soundness of the battery charging system, emission levels, efficiency of the fuel system etc. The engine analyzer is also called a scope and is very useful in subsequent tuning procedures after a complete overhaul.
Engine deposits caused by low-quality or contaminated gasoline create drivability problems, and the cure for that might be a fuel system cleaning, either by a repair shop or with a gas-tank additive. An illuminated check engine light signals when something is amiss in the emissions control system, but depending on what the issue is it could also affect fuel economy or engine performance, so don’t ignore it. A faulty oxygen sensor, for example, leaves the engine computer in the dark about how to set the air-fuel mixture, and that can result in poor fuel economy.