What is the common fault of Peugeot 508 engine?

For example, what is the common fault of Peugeot 508 engine that the subject wants to know? The relevant contents are as follows:

Failure causes of Peugeot 508 engine:

1, engine mechanical failure. For example, the pressure of each cylinder is uneven;

2, air intake system failure, such as air intake pipe leakage, etc. Excessive carbon deposition in the intake valve and intake pipe, excessive dirt on the inner wall of throttle valve and intake pipe, etc.

3. Engine management system failure. For example, the water temperature and intake air temperature signals are incorrect, and the line is faulty.

4. The ignition system is faulty. For example, the spark plug has too much carbon deposit or the gap is wrong, the high-voltage line and distributor cover leak electricity, and the ignition coil is damaged.

5, oil supply system failure. For example, due to excessive colloidal carbon deposition in the nozzle, the nozzle is not tightly closed or blocked.