What Causes Engine Misfire and Engine Fault Warning?

[DiAutumn]

There are primarily 7 reasons why the engine fault light illuminates: Sensor malfunction: This includes sensors such as coolant temperature, crankshaft position, air flow, intake 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 fault light. Fuel/oil quality issues: Failure to use the fuel and engine oil as specified by the manufacturer may cause engine wear, leading to the illumination of the fault light. Poor fuel mixture combustion: Incomplete combustion can cause engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the fault light will illuminate as a warning. Spark plug failure, ignition coil issues, fuel pump malfunction, or clogged fuel lines can all result in poor fuel mixture combustion. Turbocharging problems: Issues with the intake boost piping or turbocharger can also trigger the engine fault light. The most common is turbocharger damage, often accompanied by symptoms like oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake problems: If the vehicle's air intake is compromised, it may lead to engine pipe blockages, potentially causing the engine fault light to illuminate. A dirty or uncleaned air filter can obstruct proper airflow. Exhaust system issues: Exhaust faults may activate the engine fault light. Common causes include rear oxygen sensor failure, catalytic converter problems, or exhaust camshaft and bearing wear. Using leaded gasoline, lead/silicon-based lubricant additives, physical damage to the catalytic converter, or fuel system malfunctions can all contribute to catalytic converter failure. Anti-theft system malfunction: If the electronic anti-theft system fails or the immobilizer control unit doesn't match the engine ECU, the anti-theft system may prevent normal engine operation while illuminating the fault light. When the engine fault light appears, follow these steps: First, check if the engine operates normally. If there's noticeable shaking, black smoke emission, or other abnormalities, avoid restarting the engine—especially if the red warning light is on. If the engine starts, turn it off for 5-10 minutes. Without pressing the brake pedal, press the start button once or turn the key halfway to the "ON" position (without depressing the clutch). The vehicle will initiate a self-diagnosis upon power-up. Observe whether the fault light disappears after 5-10 seconds. If the light persists, visit a service center promptly. Technicians can retrieve trouble codes using diagnostic tools to identify and address specific issues.