Why is the engine fault light constantly on?
3 Answers
Reasons for the engine fault light staying on: 1. Poor gasoline quality leads to incomplete combustion of the air-fuel mixture in the cylinder, resulting in carbon deposits; 2. Excessive engine mileage weakens the working characteristics of spark plugs; 3. Mechanical aging of the vehicle; 4. Damage, poor contact, or signal interruption of sensors such as water temperature, crankshaft position, air flow, intake air temperature, and oxygen sensors. Hazards of the engine fault light staying on: 1. Degradation of vehicle exhaust quality, leading to environmental pollution; 2. Increased combustion chamber temperature and accelerated wear, causing premature engine damage; 3. Engine oil burning; 4. Increased engine noise, affecting driving and riding comfort.
Last time I encountered the engine warning light coming on, I immediately went to the repair shop for inspection, and it turned out to be a faulty oxygen sensor. This component monitors the oxygen content in the exhaust, and if the data is incorrect, the computer triggers an alarm. It could also be a fuel system issue, such as clogged fuel injectors or insufficient fuel pump pressure, causing the air-fuel mixture to be too rich or too lean. Pay attention to the ignition system as well; worn-out spark plugs or aging ignition coils can trigger the warning light. Also, don't forget to check the catalytic converter—if it's clogged, the emissions exceed the standard and the light will come on. Minor issues like a loose fuel cap can also cause a false alarm. If the light stays on and is accompanied by shaking or loss of power, stop the car immediately for inspection—don't push it.
I've been driving for twenty years, and the engine malfunction light coming on is actually quite common. The first thing that comes to mind is a faulty sensor, especially the crankshaft position sensor or camshaft sensor. If the data is inaccurate, the computer will report an error. The oxygen sensor on the exhaust pipe is particularly prone to failure, and replacing one costs a few hundred bucks. Another issue could be with the emission system, like a stuck exhaust gas recirculation valve or a faulty charcoal canister solenoid valve, both of which can cause the malfunction light to stay on. A commonly overlooked problem is unstable battery voltage or loose wiring connections, which can also trigger false fault codes. If the light is on but the car is running normally, you can drive to a repair shop to read the fault codes. However, if there are unusual noises or black smoke, it's safer to call for a tow truck immediately.
