What Causes the Engine Malfunction Light to Illuminate and Exhaust Emissions to Exceed Standards?

[LeChloe]

Engine malfunction light illumination and excessive exhaust emissions are related to poor gasoline quality and oxygen sensor failure. Poor Gasoline Quality: Poor gasoline quality (e.g., excessive impurities, high gum content, high sulfur content) not only affects the incomplete combustion of the air-fuel mixture in the cylinder, leading to excessive carbon deposits, but also poses risks such as clogging the fuel system and corroding components (e.g., fuel pump). It also disrupts the normal air-fuel mixture concentration, ultimately causing the engine malfunction light to illuminate and accompanied by shaking. Oxygen Sensor Failure: Most vehicles are equipped with two oxygen sensors, one before and one after the three-way catalytic converter. The front oxygen sensor monitors the air-fuel ratio under different engine operating conditions, while the ECU adjusts the fuel injection quantity and calculates ignition timing based on this signal. The rear sensor primarily checks the performance of the three-way catalytic converter. Therefore, if the oxygen sensor is damaged or the sensor connector is faulty or loose, it can lead to an excessively lean or rich air-fuel mixture, triggering the malfunction light.