First of all, hoses that make up the emission system of a car need to be checked regularly for deterioration signs such as cracks, leaks, and hardening due to high temperatures. The clamps should be tight and the hoses not distorted. In case there is any blockage in the PCV system hose, it should be cleared. The vacuum hoses need to have matching material and thickness when replaced. To detect leaks, you can use a vacuum hose as a stethoscope. In case there are bends, crimps or cracks on metal lines, then they should be replaced with seamless steel tubing.