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