When the engine malfunction light comes on, follow these steps: First, check if the engine is running normally. Look for issues such as shaking, black smoke, or difficulty starting. If any of these problems exist, avoid restarting the engine. Important note: If the light is red, do not restart the engine under any circumstances. If the engine runs normally and the vehicle can be driven, proceed to a service station as soon as possible to diagnose the issue. A service technician can easily read the fault codes using a portable diagnostic tool and perform targeted repairs based on the fault information. If the engine runs normally, the owner may also try gently reseating all wiring harness connectors, as a loose connection could be the cause. Alternatively, repeatedly turning the key to the ON position may reset the light. Generally, the engine malfunction light can illuminate due to the following seven reasons: Sensor failure: This includes sensors such as the coolant temperature sensor, crankshaft position sensor, air flow sensor, intake temperature sensor, and oxygen sensor. If these sensors are damaged, have poor contact, or lose signal transmission, the vehicle's ECU cannot accurately obtain engine data, triggering the malfunction light. Fuel or oil quality issues: If the recommended fuel or engine oil is not used, it may cause engine wear and trigger the malfunction light. Poor combustion of the air-fuel mixture: Incomplete 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. Possible causes include faulty spark plugs, ignition coils, fuel pumps, or clogged fuel lines. Turbocharger problems: Issues with the intake boost system or turbocharger can also trigger the malfunction light. The most common problem is turbocharger failure, often accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake problems: Blockages in the engine's intake system can lead to the malfunction light illuminating. A dirty or uncleaned air filter can restrict airflow and cause intake issues. Exhaust problems: Faults in the exhaust system, such as a failed rear oxygen sensor, catalytic converter, exhaust camshaft, or bearing wear, can trigger the malfunction light. The catalytic converter is the most common culprit, often damaged by leaded gasoline, improper lubricant additives, physical impact, or fuel system issues. Anti-theft system malfunction: If the vehicle's electronic anti-theft system fails or the anti-theft controller is incompatible with the engine control unit, the engine may not operate correctly, and the malfunction light will illuminate.
