What does it mean when a car shows an engine fault?
3 Answers
Here are the possible reasons why a car shows an engine fault: 1. Poor fuel quality: Low-quality fuel leads to incomplete combustion of the air-fuel mixture, failing to meet the engine's fuel performance requirements, which causes the engine fault light to illuminate. 2. Oxygen sensor malfunction: A damaged oxygen sensor or a loose/damaged sensor connector can cause the air-fuel mixture to be too lean or too rich, triggering the fault light. 3. Mass airflow sensor failure: If the mass airflow sensor or its circuit malfunctions, the ECU cannot receive the correct intake air volume signal, resulting in improper fuel control. This leads to a mixture that is either too lean or too rich, causing symptoms such as rough idling, poor acceleration, increased fuel consumption, and black smoke from the exhaust pipe, ultimately affecting the car's engine performance.
I've been driving for over a decade, and the engine warning light coming on is both common and troublesome. Generally, there are two scenarios: one is a genuine problem, and the other is a false alarm. In the case of a real fault, it could be a sensor failure, such as the oxygen sensor detecting abnormal exhaust emissions; or an issue with the ignition system, where aging spark plugs can cause engine shaking; it might also be a fuel system problem, where clogged injectors or a faulty fuel pump can affect fuel supply. If the car noticeably shakes or lacks power, it's best to pull over immediately and call for assistance. False alarms can also happen, like when using low-quality gasoline or if the electrical system gets damp. In such cases, the warning light might go off on its own after a while, but don't take chances—get to a repair shop as soon as possible to read the trouble codes.
Yesterday, my neighbor Xiao Wang asked me about this issue. He got a scare when the yellow warning light suddenly came on in his newly bought car. I told him that this warning light is essentially the car's onboard computer signaling an alert, and the reasons can vary widely. The simplest cause could be a loose fuel tank cap leading to fuel vapor leakage—just tightening it would suffice. More complex issues might involve a clogged catalytic converter or severe mechanical failures like timing chain misalignment. I advised him to first check if there are any other warning lights on the dashboard, such as the coolant temperature or oil pressure light. If only the engine light is on by itself, it's generally safe to drive to the repair shop. However, if it's accompanied by other warnings or black smoke, the engine must be shut off immediately. Regular maintenance like changing the air filter and using 95-octane fuel can prevent many such problems.
