Leaking air intake system#adapted from Wikipedia
A (cold) air intake is a device used to bring lower temperature air into a car's internal-combustion engine, to increase engine power and efficiency.
It also enhances efficiency through higher flow, and can increase the life of the engine by allowing it to run cooler.
A Leaking air intake system can cause symptoms like insufficient power on full or partial load. Additionally, it can be the reason for an unsteady idle speed or increased mileage.
If there is a leak in the air intake the only way to fix this problem is to change the air intake.
Therefor the old/factory air intake system has to be removed from the car. At this point it is highly recommended to check if there are better/custom air intakes which offer an increased engine power and efficiency than the standard/factory air intake.
Afterwards a new air filter has to be installed by attaching it to the air intake pipe. The new air filter should always be checked that it is pre-oiled and not damaged.
Finally the new air intake can be installed.