What Causes the Engine Malfunction Light to Stay On?

[VonChristian]

The engine malfunction light may stay on due to the following 7 main reasons: Sensor failure: The sensors mentioned here include the water temperature sensor, crankshaft position sensor, air flow sensor, intake air temperature sensor, oxygen sensor, etc. When these sensors are damaged, have poor contact, or experience signal interruption, the car's ECU cannot accurately obtain engine data, which will trigger the engine malfunction light. Fuel or oil quality issues: If fuel or engine oil is not added as required by the manufacturer, it may cause engine wear and trigger the malfunction light. Poor combustion of the air-fuel mixture: Poor combustion can lead to engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the malfunction light will illuminate as a warning. Issues such as spark plug failure, ignition coil failure, fuel pump failure, or clogged fuel lines can all cause poor combustion of the air-fuel mixture. Turbocharger issues: The intake boost pipeline or turbocharger can also cause the engine malfunction light to come on. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, high oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust pipe. Intake issues: If there are problems with the car's intake system, it may lead to engine pipeline blockages, 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 failures can also trigger the engine malfunction light. Common causes include rear oxygen sensor failure, catalytic converter failure, exhaust camshaft and bearing failure, with the catalytic converter being the most frequent issue. The use of leaded gasoline, lead or silicon-based lubricant additives, physical damage to the catalytic converter, or fuel system failures can easily cause catalytic converter problems. Anti-theft system failure: If the car's electronic anti-theft system malfunctions 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 trigger the engine malfunction light. If the engine malfunction light is on, follow these steps: First, check if the engine is running normally and whether there are issues such as shaking or smoke. If so, avoid restarting the engine. Note: Do not restart the engine if the red light is on. If the engine can start, 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 pressing the clutch. The car will enter self-diagnosis mode after powering on. Wait 5-10 seconds and observe whether the malfunction light on the dashboard turns off. If the malfunction light remains on, visit a service station as soon as possible. The service station can use a portable diagnostic tool to read the fault code, identify the issue, and perform targeted repairs.