Why does the car's malfunction light turn on and then off by itself?
2 Answers
In most cases where the engine malfunction light turns on and then off by itself shortly after, it does not indicate a problem with the engine itself. However, if the light frequently turns on and off repeatedly, it is necessary to check the stored fault codes, which can basically determine the source of the issue. More information about the car's malfunction light turning on and then off by itself is as follows: 1. Normal state of the malfunction light: When the car is driving and starting normally on the road, it is quite normal for the malfunction light to turn on. On one hand, it is part of the car's ECU's overall condition detection. For example, if the car's exhaust does not fall within the normal range, the engine malfunction light will turn on! Temporary faults in the car will also cause the malfunction light to turn on, and these faults may exist when the car just starts. After the car has been driven for a while or a few dozen seconds, the car's various data will become more reasonable, and the malfunction light will then turn off. Therefore, such a malfunction light does not require attention—it is just a minor episode. 2. Abnormal state of the malfunction light: When the engine actually has a fault. After using the car for some time, if the car exhibits obvious abnormal noises and a noticeable decline in performance, and the malfunction light turns on without turning off, then it must be taken very seriously. The malfunction light turning on definitely indicates a problem, and thorough checks should be conducted. Do not drive the car on the road with potential hazards.
Last time I was driving to the countryside, the warning light suddenly flashed and then went off, which is quite common. As an experienced driver with years behind the wheel, I think it might be a temporary sensor issue. For example, the oxygen sensor encountering condensation during cold starts can trigger the emission warning light when the computer detects anomalies, but the light turns off automatically once the issue resolves. Additionally, unstable battery voltage or loose power connections can also cause such intermittent problems, especially in humid weather or when driving on bumpy roads. My advice is: don’t panic right away—turn off and restart the engine a few times to observe. If the light doesn’t come back on, it’s fine. But if it happens frequently, take it to a professional shop to read the trouble codes with a diagnostic tool. After all, small issues can pile up and affect safety. Regular maintenance like cleaning the intake system and checking wire connections can prevent such awkward situations. Don’t ignore it—if spark plug misfires lead to long-term problems, it could get troublesome.
