Why does the Volkswagen EPC light come on and the car shake?

[DiEmiliano]

When the EPC light comes on in a Volkswagen Sagitar and the car shakes, it usually indicates a dirty throttle body, severe engine carbon buildup, or issues with the fuel quality. Here is the relevant information: 1. The EPC light in a Volkswagen Sagitar typically illuminates due to severe engine carbon buildup. The engine's power comes from the piston moving downward, drawing a mixture of gasoline and air into the cylinder. The upward-moving piston then compresses this mixture into a highly combustible gas, which is ignited by the spark plug. The piston is pushed by this powerful explosion, generating engine power. 2. The source of power—the air-fuel mixture—must pass through the intake valve to enter the combustion chamber. A small portion of gasoline adheres to the intake valve. Under the engine's high temperature, unburned hydrocarbons, paraffin, and gums in the gasoline are burned into carbon deposits. If the fuel injector is clogged, the sprayed gasoline will not atomize properly, leading to uneven mixing of gasoline and air. This increases the amount of gasoline that accumulates on the intake valve.