What Causes the Engine Malfunction Light to Illuminate During Normal Driving?

[OBriella]

There are primarily 7 reasons why the engine malfunction light may illuminate: Sensor Failure: This includes sensors such as coolant temperature, crankshaft position, air flow, intake air temperature, and oxygen sensors. When these sensors are damaged, have poor contact, or experience signal interruption, the vehicle's ECU cannot accurately obtain engine data, triggering the engine malfunction light. Fuel or Oil Quality Issues: Failure to use the fuel or engine oil as specified by the manufacturer may cause engine wear, leading to the illumination of the malfunction light. Poor Combustion of Air-Fuel Mixture: Incomplete combustion can result in engine carbon buildup or knocking. Once detected by the oxygen sensor and reported to the ECU, the malfunction light will illuminate as a warning. Issues such as faulty spark plugs, ignition coils, fuel pump failures, or clogged fuel lines can cause poor combustion. Turbocharger Problems: The intake boost piping or turbocharger can also trigger the engine malfunction light. The most common issue is turbocharger damage, accompanied by symptoms like oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake System Issues: Problems with the vehicle's intake system can lead to clogged engine pipes, and in severe cases, trigger the malfunction light. A dirty or uncleaned air filter can cause intake problems. Exhaust System Issues: Exhaust faults can also cause the engine malfunction light to illuminate. Common causes include faulty rear oxygen sensors, catalytic converter issues, or exhaust camshaft and bearing failures. The catalytic converter is most frequently affected, often due to the use of leaded gasoline, lead/silicon-based lubricant additives, physical damage, or fuel system malfunctions. Anti-Theft System Malfunction: If the vehicle's electronic anti-theft system fails or if there is a mismatch between the anti-theft controller and the engine ECU, the anti-theft system may prevent the engine from operating normally, accompanied by the illumination of the malfunction light. If the engine malfunction light illuminates, follow these steps: First, check if the engine is running normally. Look for symptoms like shaking or black smoke. If present, avoid restarting the engine. Note: Never 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 enter self-inspection mode. After 5-10 seconds, observe if the malfunction light turns off. If the light remains on, visit a service center as soon as possible. Technicians can use a portable diagnostic tool to read fault codes, identify the issue, and perform targeted repairs.