Characteristic signs of serious mechanical damage usually appear after a run of hundreds of thousands of kilometers. Parts that fail unexpectedly are usually small, easily replaceable, and their failure does not interfere with vehicle operation.
If there is a failure of one or another node, unit or system, you first need to understand where to start the search. Sometimes it's obvious, and sometimes you have to search consistently. An owner who makes random replacements and adjustments can sometimes even succeed in fixing the problem (or its signs), but this is irrational, because is usually a half-measure, and not a way out of the situation. It is better to think calmly, imagine the principle of operation and the device of the corresponding node or system, and by the method of successive elimination, find and eliminate the cause. Always be aware of any signs and symptoms that indicate the beginning of a damage process - loss of power, high or low readings from sensors, unusual smells and noises, etc. Remember that the failure of parts such as fuses or spark plugs may indicate some hidden damage to other components and parts.
The following is a troubleshooting guide that is easy to use for the most common vehicle problems. These malfunctions and their possible causes are grouped into sections, such as: engine, cooling system, etc. Parentheses indicate the chapter and/or section to be referred to. When troubleshooting, follow some basic principles. They are:
Check for initial symptoms. Check that you have correctly identified the features before starting work. This is especially important if you are determining the cause of the problem for someone else who cannot describe the symptoms accurately enough.
Don't overlook the most obvious reasons. For example, if the engine does not start, check if there is fuel in the tank (Don't take anyone's word for it, and don't rely on the fuel gauge!). If an electrical circuit breaks, look for a disconnected or torn wire or a blown fuse before removing the tester.
Eliminate the cause of the problem, not the effect. If you need to charge the battery regularly, you need to find and eliminate the cause (replace battery or alternator), otherwise the battery will continue to discharge. Likewise, replacing oil-contaminated spark plugs will result in normal operation (at least for a while), but remember that the cause of pollution (if the spark plugs are of the recommended type) needs to be identified and eliminated.
Even new parts need to be checked. Remember that the most «new» item may be defective (especially if it hangs in the trunk for several months), and do not rule out parts when troubleshooting, even if they are new or recently installed. Having finally determined the cause of the damage, you may realize that it was obvious from the very beginning.