What to Do When the Engine Malfunction Light Is On?
2 Answers
If the engine malfunction light is on, you can follow these steps: First, check whether the engine is running normally, such as if there is any shaking, black smoke, or difficulty starting. If any of these issues are present, try not to start the engine again. Especially note that if the red light is on, do not start the engine under any circumstances. If the engine is running normally and the car can be driven, go to a service station as soon as possible to diagnose the issue. The service station can easily read the fault code using a portable diagnostic tool to obtain targeted repair information. If the engine is running normally, the owner can also try gently reinserting all wiring harness connectors, as a loose connection might be the cause. Alternatively, repeatedly turning the key to the ON position may help reset the light. Generally, the engine malfunction light may be triggered by 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 their signals are interrupted, the car's ECU cannot accurately obtain engine data, triggering the malfunction light. Fuel or oil quality issues: If fuel or engine oil is not added according to the manufacturer's specifications, it may cause engine wear, leading to the malfunction light turning on. Poor combustion of the air-fuel mixture: Poor combustion can cause engine carbon buildup or knocking. When 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 pumps, or clogged fuel lines can lead to poor combustion. Turbocharger issues: Problems with the intake boost piping or turbocharger can also trigger the engine malfunction light. The most common issue is a damaged turbocharger, often accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake problems: If there is an issue with the car's air intake, it may lead to clogged engine pipes, which can trigger the malfunction light in severe cases. A dirty or uncleaned air filter can cause intake problems. Exhaust problems: Exhaust system faults can also cause the engine malfunction light to turn on. Common causes include faults in the rear oxygen sensor, catalytic converter, exhaust camshaft, or bearings. The catalytic converter is the most frequently affected component. Using leaded gasoline, lead- or silicon-containing lubricant additives, physical damage to the catalytic converter, or fuel system issues can easily cause catalytic converter failure. Anti-theft system failure: If the car's electronic anti-theft system malfunctions or the anti-theft controller does not match the engine's electronic controller, the anti-theft system may prevent the engine from operating normally, also triggering the malfunction light.
I just encountered the engine warning light coming on, and my first reaction was not to panic. While the car was running, if the light suddenly comes on, it could be an issue with the emissions system, such as a faulty oxygen sensor or a clogged catalytic converter. After stopping, I would first check if the fuel cap is tightened properly—if it was loose causing a vacuum leak, tightening it might turn the light off. If the light stays on or flashes, it's not safe to continue driving at high speeds, as it could lead to engine overheating or worse. I must remind everyone that this is quite dangerous and affects driving safety. The best course of action is to immediately slow down, pull over to inspect, and then call the nearest 4S shop or repair station to use professional tools to read the fault codes and identify the root cause. For prevention, I check the engine oil and air filter every month to ensure proper maintenance. In simpler terms, timely action is key—don’t wait for a small issue to turn into a major repair.
