Why does the engine light come on after starting the car?
3 Answers
Reasons why the engine light comes on after starting the car: 1. Sensor issues, including coolant temperature, crankshaft position, air flow, intake temperature, oxygen sensors, etc. When these sensor signals are interrupted, the car's ECU cannot accurately obtain engine data, which will cause the engine fault light to illuminate; 2. Engine spark plug failure, ignition coil failure, fuel pump failure, fuel line blockage, etc., can all cause poor combustion of the engine's air-fuel mixture; 3. Fuel quality issues, including fuel and engine oil. If the owner does not add them as required, long-term use will cause engine wear, and the engine fault light will come on; 4. Poor engine maintenance is a common cause of the engine fault light coming on; 5. Intake problems. The engine needs air intake during combustion. If the car's air filter is not clean and not cleaned regularly, it will affect the car's air intake. Over time, blockages can occur, and in severe cases, the engine fault light will come on.
A few days ago, the engine light suddenly came on when I started the car, which gave me quite a scare. As a driving novice, I remember my instructor mentioning that this could be due to sensor issues, like a faulty oxygen sensor, or clogged fuel lines causing incomplete combustion. When the light turns on, the car might seem fine, but you should never ignore it. Last time I didn't address it, and after a few days, I felt a lack of power on the highway. The repair shop said there were fault codes in the emission system, and it cost some money to fix before I felt at ease. For daily driving of an older car, a dirty air filter can also easily trigger the light. It's recommended to check if the fuel cap is tightened every time you refuel, as a loose cap can cause a leak alarm. If the light stays on, it's best to visit a professional repair shop to scan for specific faults with a diagnostic tool, to prevent minor issues from turning into major troubles.
Having driven for over thirty years, I've seen quite a few instances of the engine light coming on. Common causes include worn spark plugs or aging ignition coils leading to incomplete combustion, which triggers the computer's automatic warning. It could also be an issue with the oil pump, causing poor lubrication and making the engine produce a knocking sound. In fact, even minor faults in the vehicle's emission system can turn on the light, such as a clogged catalytic converter, which you might notice during highway driving as a sudden spike in fuel consumption. As a seasoned driver, I'd suggest not rushing to spend big money right away. First, try restarting the engine or taking a short drive to see if the light goes off. If it stays on, check for loose battery terminals—last time, my light was on due to corroded terminals, and it was fine after cleaning. Regular maintenance like changing the oil and air filter can help reduce such issues.
