What's the reason for the engine fault light being on and the car not starting?
2 Answers
Engine fault light being on and the car not starting can be caused by the following reasons: Poor quality, non-compliant gasoline: Shortly after refueling, the engine fault light on the car's dashboard comes on; this is usually because low-quality gasoline was added at an unregulated gas station, causing incomplete combustion of the air-fuel mixture during engine operation, which triggers the engine fault light. This does not affect driving safety but may harm the engine to some extent. Oxygen sensor failure: Modern cars are equipped with two oxygen sensors, one before and one after the three-way catalytic converter. The front oxygen sensor detects the air-fuel ratio under different engine conditions, while the ECU adjusts the fuel injection amount and calculates the ignition timing based on this signal. The rear sensor mainly monitors the performance of the three-way catalytic converter. Therefore, if the oxygen sensor is damaged or the sensor connector is damaged or loose, it can cause the air-fuel mixture to be too lean or too rich, leading to the fault light coming on.
A few days ago, my car had the same issue—the engine yellow light came on, and there was no response at all when trying to start it, which left me in a panic. After checking, the possible causes could be a dead battery or a faulty starter. A simple approach is to first check if other dashboard lights are working; if none are lit, it’s likely the battery is dead. Try jump-starting it with a friend’s car. If it starts with a jump, then it’s a battery issue, and a replacement costs around 300-500 RMB. If there’s a cranking sound but the car won’t start, it might be due to a fuel pump not supplying fuel or a faulty ignition coil. It’s best not to force it—call a tow truck and take it to a professional repair shop where they can accurately read the fault codes with a diagnostic tool. Personally, I check my battery’s fluid level and charging status monthly to avoid such troubles. If the yellow light is on but the car still runs, get it fixed ASAP to prevent major engine repairs. Remember, safety first—if stranded on the roadside, turn on the hazard lights and wait for help.
