Why does the car idle shake and the engine fault light come on?

[EvelynFitz]

Car idle shaking and engine fault light coming on are caused by severe engine carbon deposits, dirty throttle, spark plug failure, poor combustion of engine mixture, etc. The car may also experience phenomena such as knocking and shaking. If the car's mixture is too lean, it may also exhibit symptoms of weak acceleration. The engine's idle speed can be adjusted by modifying the throttle size, with the normal idle speed typically ranging between 550 to 800 revolutions per minute. Problems with the car's idle speed can lead to unusual engine noises. When the accelerator pedal is released during engine operation, the engine enters an idle state. In this state, the engine only needs to overcome its own resistance to operate, resulting in relatively low fuel consumption. Both excessively high and low idle speeds can lead to driving issues.

[LincolnMarie]

When my car idles and shakes like it's dancing, with the engine warning light on, I know there's a problem. Having driven for over 20 years, I've encountered this issue several times. The most likely causes are worn-out spark plugs or faulty ignition coils, leading to cylinder misfires and uneven combustion. Mixture problems are also common, such as a dirty mass airflow sensor or clogged fuel injectors, causing insufficient fuel supply and resulting in shaking. Thick carbon deposits can make idle particularly unstable. When the warning light comes on, it means the onboard computer has detected an error. It's best to use a diagnostic tool to read the trouble codes and identify the cause before making repairs. Don't delay—I once waited too long, and minor shaking turned into severe shaking, even damaging the engine. I recommend regularly replacing spark plugs and performing maintenance to prevent carbon buildup. Fuel additives can also help clean the fuel system. In short, start with simple self-checks, and if that doesn't work, seek professional help.

[JackDella]

In automotive repair work, cases of idle shaking with the check engine light on are frequently encountered. I understand this is the result of various systems being out of sync. Spark plug or ignition system failures are the most common, but EGR valve leaks can cause excess exhaust gas to enter, leading to a lean mixture and shaking. Clogged or non-functioning fuel injectors may also result in insufficient fuel supply. Faulty sensors like the oxygen sensor can disrupt the air-fuel ratio. Unstable voltage from the battery or alternator can also affect system control. The first step should be to read the fault codes to pinpoint the issue, avoiding blind part replacements. Sometimes, aging wiring or poor connections cause intermittent shaking, and a thorough inspection can save money. Additionally, be mindful that overheating or oil pressure issues may exacerbate the problem. Address it promptly to prevent damage to the catalytic converter.

[LeZoey]

As a car enthusiast, I pay special attention to the issue of idle vibration and warning lights, where prevention is key. Idle vibration is often caused by neglected maintenance, such as failing to replace spark plugs on time or a dirty air filter affecting air intake. Engine carbon buildup is an invisible killer that worsens vibration over time. A lit warning light indicates the sensor has detected an abnormality, possibly due to an oxygen sensor malfunction. I recommend performing inspections every 5,000 kilometers, cleaning the throttle body and fuel injectors, and adding fuel system cleaner to reduce carbon buildup. When it occurs, avoid high-speed driving and check the ignition system after stopping. Developing good habits can prevent 90% of vibration issues.