What Causes the Engine Fault Light to Illuminate During Self-Check in the Nissan X-Trail?

[DelAmelia]

The engine fault light in the Nissan X-Trail may illuminate due to the following 7 main reasons: 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 signal interruption occurs, the vehicle's ECU cannot accurately obtain engine data, triggering the engine fault light. Fuel or Oil Quality Issues: If fuel or engine oil is not added as per the manufacturer's requirements, it may cause engine wear, leading to the fault light illuminating. Poor Combustion of Air-Fuel Mixture: Poor combustion can result in engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the fault light will illuminate as a warning. Issues like spark plug failure, ignition coil failure, fuel pump failure, or clogged fuel lines can cause poor combustion. Turbocharging Problems: The intake boost pipeline or turbocharger can also trigger the engine fault light. The most common issue is turbocharger damage, accompanied by symptoms like oil leaks, high oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake Problems: If the vehicle's intake system is compromised, it may lead to clogged engine pipelines, and in severe cases, the engine fault light will illuminate. A dirty air filter that isn't cleaned regularly can cause intake issues. Exhaust Problems: Exhaust faults can also cause the engine fault light to illuminate. Common causes include rear oxygen sensor failure, catalytic converter issues, exhaust camshaft and bearing failure, with the catalytic converter being the most frequent problem. Using leaded gasoline, lead or silicon-based lubricant additives, physical damage to the catalytic converter, or fuel system malfunctions can easily lead to catalytic converter failure. Anti-Theft System Malfunction: If the vehicle's electronic anti-theft system fails or if the anti-theft controller does not match the engine's electronic controller, the anti-theft system can prevent the engine from operating normally, causing the engine fault light to illuminate. If the engine fault light illuminates, follow these steps: First, check if the engine is running normally, looking for signs like shaking or black smoke. If such issues are present, avoid restarting the engine. Note: Do not restart the engine if the light is red. 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 upon powering up. Wait for 5-10 seconds to see if the fault light turns off. If the fault 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.