What Causes the Vehicle's Engine Malfunction Light to Stay On?
2 Answers
There are primarily 7 reasons for the engine malfunction light to illuminate: Sensor failure: The sensors mentioned here include coolant temperature, crankshaft position, air flow, intake air temperature, oxygen sensors, etc. When these sensors are damaged, have poor contact, or experience signal interruption, the vehicle's ECU cannot accurately obtain engine data, leading to the illumination of the engine malfunction light. Fuel quality issues: If fuel and engine oil are not added as required by the manufacturer, it may cause engine wear, resulting in the malfunction light turning on. 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. Spark plug failure, ignition coil failure, fuel pump failure, and fuel line blockages can all cause 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, high oil consumption, reduced power, metallic noises, and blue or black smoke from the exhaust pipe. Intake issues: If the vehicle's intake system has problems, it may lead to engine pipeline blockages, and in severe cases, the engine malfunction light will illuminate. A dirty air filter that is not cleaned regularly can cause intake problems. Exhaust issues: Exhaust system failures can also cause the engine malfunction light to illuminate. Common causes include rear oxygen sensor failure, catalytic converter issues, exhaust camshaft and bearing failures, with the catalytic converter being the most frequent culprit. The use of leaded gasoline, lead or silicon-containing lubricant additives, physical damage to the catalytic converter, and fuel supply system failures can all easily lead to catalytic converter problems. Anti-theft system failure: If the vehicle'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 the engine malfunction light will illuminate. If the engine malfunction light is on, follow these steps: First, check if the engine is running normally, and look for issues such as shaking or black smoke. If present, avoid restarting the engine. Note: Do not restart the engine if the red light is on. If the engine can be started, turn it off and wait for 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 after powering on. Wait for 5-10 seconds and observe if the malfunction light on the dashboard turns off. If the malfunction light remains on, visit a service station as soon as possible to identify the cause. The service station can use a portable diagnostic tool to read the fault codes, obtain fault information, and perform targeted repairs.
I've been driving a taxi for over a decade, and the engine malfunction light staying on is a common sight. More often than not, it's an issue with the oxygen sensor. This little device measures the oxygen levels in the exhaust. Once it gets clogged with carbon deposits or burns out, the inaccurate signals will trigger the light. It could also be a problem with the combustion system, like insufficient cylinder pressure or clogged fuel injectors, which can make the engine struggle. Just last month, my car had this issue, and it turned out to be caused by bad gasoline that poisoned the catalytic converter. The worst-case scenario is a short circuit or a faulty ECU computer board. In such cases, you need to rush to the repair shop to read the fault codes with a computer. Driving with these issues can easily wreck the engine.
