The main function of the air filter is to filter the air entering the engine and prevent impurities such as dust and sand particles from entering the cylinder. When the air filter is clogged, it will have a series of negative impacts on the engine:

Reduced intake volume, Loss of Power:
A clogged filter is like a narrow passage, hindering fresh air from entering the cylinder smoothly.
Air is an essential component for combustion. A reduction in the intake volume indicates insufficient oxygen for each combustion, resulting in a richer mixture (more oil and less gas).
This will lead to a decrease in combustion efficiency, and the engine will be unable to generate sufficient power, which is manifested as weak acceleration of the vehicle, difficulty climbing slopes, and a reduction in the maximum speed.

Increased fuel consumption:
To make up for the lack of oxygen, the electronic control unit (ECU) of the engine may attempt to adjust the fuel injection volume, or the mixture itself may be too rich due to insufficient intake.
Incomplete combustion or overly rich mixtures can both lead to increased fuel consumption, which is what we often refer to as "high fuel consumption".

Increased Carbon Deposits:
Incomplete combustion will produce more hydrocarbons and carbon deposits.
These carbon deposits will settle on parts such as valves, the top of pistons, combustion chambers, spark plugs (or fuel injectors), etc.
Excessive carbon deposits may lead to problems such as poor valve closure, piston ring jamming, and poor ignition, further affecting engine performance and even causing engine knocking.

Increased Risk of Engine Overheating
Although the air filter itself does not directly dissipate heat, the decline in combustion efficiency and power loss caused by insufficient intake air will make the engine work more difficult under the same load and generate more ineffective heat.
At the same time, if the engine operates at a high load continuously to obtain power, it will also increase the thermal load of the engine.

Rough Idle or Stalling:
Poor air intake can lead to uneven air intake in each cylinder or insufficient overall air intake, causing the engine to run unsmoothly.