What Causes the Engine Warning Light to Flash and the Car to Shake?
3 Answers
The reasons for the engine warning light flashing and the car shaking are: 1. Damaged, poorly connected, or interrupted sensors; 2. Poor engine maintenance; 3. Low-quality fuel or engine oil; 4. Incomplete combustion of the air-fuel mixture; 5. Faulty spark plugs or ignition coils; 6. Fuel pump failure or clogged fuel lines; 7. Clogged air filter. The solutions for the engine warning light flashing and the car shaking are: 1. Use fuel additives to clean the entire fuel system; 2. After cleaning the engine, use higher-octane gasoline; 3. Use high-quality fuel additives to improve fuel cleanliness; 4. Replace the catalytic converter.
My old Focus had the same issue last month, with the warning light flashing like a disco and the car shaking so badly I couldn't even keep my phone steady. The main focus should be on checking the ignition system—worn spark plugs or faulty ignition coils are particularly prone to causing a cylinder misfire. Last time, the mechanic used a diagnostic tool and found it was a misfire in cylinder 3, which was fixed by replacing the spark plugs with a set of NGK platinum ones. Another friend's car had shaking caused by clogged fuel injectors, which was resolved after cleaning them. If you encounter this situation, don't keep driving—pull over immediately and wait for a tow truck to take it in for inspection.
If the engine's yellow light is flashing accompanied by shaking, it's most likely due to incomplete combustion of the air-fuel mixture. A common cause is ignition coil leakage - just one faulty coil can make all four cylinders stop working. Insufficient fuel pump pressure can also cause this; I've personally seen cases where the fuel pressure gauge needle went haywire in repair shops. Another trigger is excessive carbon buildup in the throttle body restricting airflow, which can be temporarily relieved by spraying and cleaning with carburetor cleaner. The most troublesome issue is oxygen sensor failure - its false readings can completely disrupt the entire fuel trim system. Nowadays many repair shops use oscilloscopes to monitor real-time combustion conditions in each cylinder, which is more accurate than just reading trouble codes.
