Why is the engine fault light on when the car is not started?
2 Answers
When the engine fault light is on without the car being started, it indicates the vehicle is performing a self-check, meaning the engine is not yet operational. Before ignition, the car enters a self-diagnostic state, and this light (the engine fault light) will illuminate. It will turn off once the car is started normally. An engine is a machine capable of converting other forms of energy into mechanical energy, originating in the UK. It can refer to both the power generation device and the entire machine including the power unit (such as gasoline engines, aircraft engines). Types include internal combustion engines (e.g., gasoline engines), external combustion engines (e.g., Stirling engines, steam engines), and electric motors, among others.
I've driven quite a few cars, and this situation is quite common. When you turn the car key to the ignition position but the engine doesn't start, that warning light coming on is the vehicle's self-check system at work, just like a phone's screen test during startup when all indicators light up briefly to confirm normal operation. If the light only stays on for a few seconds and then goes off, it's completely normal, indicating the system hasn't detected any issues. If it remains lit, there might be a potential problem—it could be the oxygen sensor, ignition system, or emission sensor storing a trouble code. I've encountered this before, and it turned out to be a minor issue with the exhaust system causing the light to stay on. Never ignore it, as it suggests there might be an engine performance issue that could affect fuel efficiency or even lead to a breakdown over time. I recommend using an OBD scanner to read the trouble code as soon as possible or driving to a repair shop for a scan to prevent small problems from escalating. Regular maintenance can also help prevent such issues, ensuring your car stays safe and reliable.
