What are the reasons for the engine warning light in Mercedes-Benz W221?

[ElenaLee]

Sensor issues, car maintenance problems, fuel quality issues, poor combustion of the air-fuel mixture, engine intake problems, turbocharging issues, exhaust problems, and the anti-theft system are the main reasons for the engine warning light to illuminate. Additionally, when the car is started, the vehicle performs a self-check on the engine system. Normally, the engine warning light should turn off after the self-check is completed. If it remains on for an extended period, it is advisable to visit a repair station promptly for professional assistance to diagnose and eliminate potential safety hazards. The following is a detailed explanation of each type of fault: Sensor issues: Sensors include coolant temperature, crankshaft position, air flow, intake temperature, oxygen sensors, etc. When these sensors are damaged, have poor contact, or experience signal interruptions, the car's ECU cannot accurately obtain engine data, causing the engine warning light to illuminate. In such cases, it is essential to visit a repair center promptly for professional diagnosis and elimination of safety hazards. Maintenance issues: Poor engine maintenance is the most common cause of the engine warning light illuminating. Vehicles have specific maintenance cycles. If maintenance is not performed on schedule, combined with poor driving habits, the engine's operational burden increases, eventually triggering the engine warning light to alert the owner of a fault. Fuel quality issues: This refers to both fuel and engine oil. The fuel used in cars typically has a specific octane rating, while engine oil can be semi-synthetic or fully synthetic. Manufacturers usually recommend which fuel octane rating and type of engine oil to use. If the owner fails to adhere to these recommendations, prolonged use can lead to engine wear, causing the warning light to illuminate. It is important to use the correct fuel octane rating and appropriate engine oil as specified for the vehicle. Poor combustion of the air-fuel mixture: Faulty spark plugs, ignition coils, fuel pumps, or clogged fuel lines can lead to poor combustion of the air-fuel mixture in the engine. This results in engine carbon buildup or knocking, which is detected by the oxygen sensors and reported to the ECU, triggering the warning light as an alert. Intake problems: Engine combustion requires air intake, and the air filter plays a crucial role in this process. If the air filter is dirty or not cleaned regularly, it can affect the engine's air intake, potentially leading to blockages over time. In severe cases, this can cause the engine warning light to illuminate. Turbocharging issues: Problems with the intake turbocharging pipes or the turbocharger itself can also cause the engine warning light to illuminate. The most common issue is a damaged turbocharger, accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Exhaust problems: Faults in the rear oxygen sensor, catalytic converter, exhaust camshaft, or bearings can trigger the engine warning light. The most common issue is a faulty catalytic converter. Factors such as using leaded gasoline, lead- or silicon-based oil additives, physical damage to the catalytic converter, or fuel system malfunctions can contribute to catalytic converter failure. Anti-theft system: If the car's electronic anti-theft system malfunctions or if the anti-theft controller is incompatible with the engine's electronic controller, the anti-theft system can prevent the engine from operating correctly, causing the warning light to illuminate. Solutions for the engine warning light: If the engine warning light is on and the car cannot start, this may be due to a faulty fuel pump or ignition components. It is recommended to call for assistance immediately. If the engine warning light is on and the car can still be driven but exhibits severe shaking or loss of acceleration, pull over safely and call for roadside assistance. If the engine warning light is on but the car drives normally, this may indicate a faulty sensor. In this case, you can continue driving cautiously at low to moderate speeds but should visit a repair shop as soon as possible to diagnose and address the issue.