Why does the engine malfunction indicator light turn on and then off by itself?
3 Answers
It is normal for the engine malfunction indicator light to turn on and then off. When the vehicle's power is turned on but the engine is not yet started, various warning lights on the dashboard, including those for the engine, coolant temperature, battery, airbag, etc., will illuminate simultaneously. Once the vehicle is started, these lights will automatically turn off. This is the vehicle's self-diagnostic function in operation, which is a normal phenomenon. Here is additional information: 1. Vehicle self-diagnosis: This occurs because vehicles are equipped with a self-protection system designed to inform the driver of internal changes in the vehicle's condition, allowing them to prepare accordingly. This helps prevent accidents caused by vehicle malfunctions. Therefore, the engine light turning on and then off is normal, and there is no need for excessive concern. 2. How to handle a flashing engine malfunction indicator light: (1) If the car cannot start, this may be due to a fuel pump or ignition component failure. In this case, call for assistance immediately. (2) If the malfunction light is on but there are no noticeable driving issues, this might simply indicate a sensor malfunction. You can continue driving temporarily, but it is advisable to drive at low speed and visit a repair shop as soon as possible. (3) If the engine malfunction light is on and the vehicle can still be driven but exhibits severe shaking, lack of acceleration power, or similar symptoms, you should stop the vehicle promptly and call for roadside assistance.
I encountered a similar situation a few days ago. The engine warning light suddenly came on, which scared me so much that I immediately pulled over. However, after driving for about ten minutes, it turned off by itself. Later, I asked my mechanic friend, and he said it’s quite common—it could be a momentary issue with the oxygen sensor or the exhaust system, such as the exhaust sensor occasionally falsely reporting excessive emissions. After the engine adjusted itself, everything returned to normal. The light turning off indicates that the temporary fault was automatically resolved, but you shouldn’t let your guard down. The fault code might still be stored in the car’s computer, so it’s recommended to visit a 4S shop or a reputable repair shop to read the historical records and rule out potential risks. Develop good driving habits, such as regularly checking fluid levels and sensor conditions. Addressing minor issues early can prevent major troubles—don’t be like me, waiting until the light comes on to panic.
I've been in auto repair for over a decade and have seen countless cases of the engine light coming on and off. Usually it's the engine control unit detecting anomalies like temporary ignition coil misfires or short circuits in intake sensors. The system triggers an instant warning, but the light goes off when the vehicle restarts or resumes normal operation. However, this signal shouldn't be ignored - fault codes are often stored in the OBD diagnostic system, requiring professional scanning tools to confirm permanent damage. I've had customers who skipped inspection only to face worsening engine vibrations later. My advice: get a basic code reader for self-diagnosis or visit a repair shop promptly. Don't let minor issues escalate into costly overhauls. For maintenance, keep sensors clean to minimize dust interference.
