Why does the engine fault light turn on and then disappear after restarting?
3 Answers
The reasons why the engine fault light turns on and then disappears after restarting: 1. The fault light illuminates because the engine control computer detects a fault in the control system. The computer also records the fault code and some key data at the time of the fault; 2. The main reason for the engine fault light turning on is excessive carbon deposits in the throttle or inside the engine, causing an imbalance in the air-fuel mixture ratio; 3. If you frequently engage high gears at low engine speeds, it can also lead to this phenomenon. For intermittent faults, if the fault does not reappear within several operating cycles, the fault light may turn off, but the fault code will still be recorded in the computer. It is recommended to visit a repair station to check the fault code. The repair station can conduct further inspections based on the fault code to identify the root cause of the fault.
I was driving out when suddenly the check engine light came on, and my heart skipped a beat. But after restarting the car, it disappeared again. This is most likely caused by a minor sensor glitch, like the oxygen sensor detecting abnormal exhaust data—perhaps due to momentary fuel contamination causing inaccurate readings, which triggers a false error and lights up the warning. After restarting, the system resets parameters during self-check, and the light turns off. However, don’t take it lightly—this is often an early warning sign. My advice is to promptly visit a repair shop to scan for trouble codes using an OBD scanner. Even if the light is off, the error history remains stored in the system and can reveal the root cause. Ignoring it could turn a small issue into a major one—next time the light comes on, it might indicate serious engine trouble affecting driving safety. Don’t skimp on the inspection fee; replacing parts like spark plugs or sensors usually costs just a few hundred bucks.
As a car repair enthusiast, I've found that when the engine light flashes briefly and disappears after a restart, there can be multiple causes. It might be due to poor contact in the ignition coil or spark plugs, causing intermittent sparks that affect engine operation. The system triggers a warning light upon detecting instability, but a restart with some cooling time often resolves it temporarily. However, don't just celebrate the light going off—underlying issues may persist, such as wiring degradation or sensor sensitivity causing false alarms. The most reliable solution is to use a multimeter to test the circuits and tighten any loose connections. Replace aging components when necessary to prevent the dangerous scenario of the light coming on with engine shuddering during high-speed driving. Consistent regular maintenance reduces such faults, saving on major repair costs and ensuring peace of mind on the road.
