What Fault Causes the Engine Malfunction Light to Stay On?

[JordanRose]

The engine malfunction light may stay on due to the following 7 main reasons: Sensor malfunction: The sensors mentioned here include those for coolant temperature, crankshaft position, air flow, intake air temperature, oxygen, etc. When these sensors are damaged, have poor contact, or experience signal interruption, the vehicle's ECU cannot accurately obtain engine data, which can trigger the engine malfunction light. Fuel quality issues: Failure to add fuel and engine oil as required by the manufacturer may cause engine wear, leading to the malfunction light turning on. Poor combustion of the air-fuel mixture: Poor combustion can cause engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the malfunction light will illuminate as a warning. Spark plug failure, ignition coil failure, fuel pump failure, and fuel line blockage can all lead to poor combustion of the engine's air-fuel mixture. Turbocharging issues: The intake turbocharging pipeline and turbocharger can also cause the engine malfunction light to illuminate. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, and blue or black smoke from the exhaust pipe. Intake issues: If the vehicle's intake system encounters problems, it may lead to engine pipeline blockage, and in severe cases, trigger the engine malfunction light. A dirty air filter that is not cleaned regularly can cause intake problems. Exhaust issues: Exhaust system faults can also cause the engine malfunction light to illuminate. The rear oxygen sensor, three-way catalytic converter, exhaust camshaft, and bearing failures are all potential causes of exhaust problems, with the three-way catalytic converter being the most common. Using leaded gasoline, lead or silicon-containing lubricant additives, physical damage to the catalytic converter, or fuel supply system failures can easily lead to three-way catalytic converter issues. Anti-theft system malfunction: If the vehicle's electronic anti-theft system fails, or if the anti-theft controller does not match the engine electronic controller, the anti-theft system can prevent the engine from operating normally and cause the malfunction light to illuminate. If the engine malfunction light is on, follow these steps: First, check if the engine is running normally, looking for symptoms such as shaking or smoke. If present, avoid restarting the engine. Note: Do not restart the engine if the red warning light is on. If the engine can be started, turn it off and wait 5-10 minutes. Without pressing the brake, press the start button once or turn the key halfway to the 'on' position without depressing the clutch. The vehicle will perform a self-check upon powering up. Observe the dashboard after 5-10 seconds to see if the malfunction light turns off. If the light remains on, visit a service station as soon as possible for diagnosis. The service station can use a portable diagnostic tool to read the fault codes, identify the issue, and perform targeted repairs.