What is the reason why the engine fault light sometimes turns on and sometimes off?

[LondonRose]

The reason why the engine fault light sometimes turns on and sometimes off is: there is a fault in the engine. When it does not affect normal driving, the engine fault light will turn off, and when there is a fault, it will light up yellow or red. The methods to eliminate the engine fault light are: 1. Disconnect the negative terminal of the engine battery, wait for 30 seconds, and then reconnect it to eliminate the fault; 2. Go to a 4S shop for detection and elimination. The methods to maintain the engine are: 1. Use high-quality engine oil; 2. Use qualified coolant; 3. Regularly clean the water tank scale; 4. Regularly remove carbon deposits from the car; 5. Replace the car's three filters on time; 6. Maintain a reasonable engine speed.

[VonSophia]

Over the years, I've repaired countless cars and encountered situations where the engine light flickers on and off—more often than not, it's due to sensor issues. For example, an aging oxygen sensor or excessive dust can cause inaccurate signals; or loose wiring connectors that short-circuit in humid weather. Wiring faults are often overlooked, yet a simple tightening can fix them. However, worn spark plugs can also trigger false alarms, and ignoring them long-term can increase fuel consumption by 30% and damage the engine. I recommend keeping an OBD scanner in the car—plug it in to read fault codes quickly and accurately. Regularly cleaning the engine bay helps prevent minor issues from escalating. Never wait until a breakdown to act—safe driving is paramount.

[MacReese]

My old car's lights have been flickering recently, which really made me uneasy. It turned out to be a fuel pump issue causing unstable pressure, and the acceleration felt sluggish when the lights came on. If left unfixed for too long, the entire fuel pump could fail, costing over a thousand to replace; whereas fixing minor issues early saves both time and money. It's also worth checking the ignition coils and exhaust pipe, as similar problems are common in older vehicles. I believe developing a habit of pre-start self-checks, like tapping the wiring harness, can prevent many unexpected issues. Especially on long trips, if the lights come on, pull over safely and turn on the hazard lights to avoid danger.

[LaWillow]

Don't panic when encountering flashing car lights as a beginner, it's usually a minor false alarm. Try restarting the engine and check if the fuel tank cap is tightened; a loose cap can trigger false signals, and the light turning off means no major issue. Alternatively, poor contact in the wiring near the wipers may be affected by rain, so secure it with some tape. In severe cases, read the OBD code to locate the problem, which can often be fixed with a minor repair costing just tens of yuan. However, if the light comes on frequently, don't ignore it. Short trips may be fine, but long-distance travel carries higher risks.