Why does the car engine shake and the malfunction indicator light come on?
2 Answers
The reasons for the car engine shaking and the malfunction indicator light coming on are as follows: 1. Poor quality gasoline that does not meet standards: This is usually caused by refueling with low-quality gasoline at non-standard gas stations, leading to insufficient combustion of the air-fuel mixture during engine operation and the illumination of the engine malfunction light. This does not affect driving safety but may more or less harm the engine. 2. Oxygen sensor malfunction: 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 operating conditions, while the ECU adjusts the fuel injection quantity 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, triggering the malfunction light.
I encountered the same situation last year. While driving, the engine suddenly started shaking violently, like sifting rice, and the warning light was glaringly bright, which scared me into pulling over immediately. At the time, I suspected it might be an issue with the ignition system, such as worn-out spark plugs or excessive carbon buildup, causing uneven combustion and making the engine run roughly. Later, at the repair shop, they confirmed the spark plugs were indeed burnt out. They also recommended regular fuel system cleaning and air filter checks to prevent carbon buildup. Looking back now, this is definitely not something to delay—severe shaking and warning lights indicate the system has detected a major fault, possibly due to uncontrolled air-fuel ratio or a failed sensor. If not addressed promptly, engine damage could lead to even costlier repairs. So, I suggest you stop the car immediately instead of pushing through, and let a professional mechanic scan the trouble codes with a diagnostic tool.
