Car Check Engine Light On? Common Reasons Behind This Warning
Car Check Engine Light On? Common Reasons Behind This Warning
by SAI AUTO CARE
Monday February 23, 2026
Most drivers panic and misunderstand when the car’s check engine light comes on, thinking there is something wrong under the hood, but it simply means the car’s diagnostic system has detected an issue. The check engine light is a simple warning indicator present in the car’s dashboard. Yes, you must get off the road when you see your car check engine light on.
The check engine on car means that the car has an issue, and it might be minor or major depending on the error displayed on the dashboard. The car itself communicates with the driver who drives or tows it to the car engine mechanic to ensure the driver’s safety and avoid high-cost repairs due to delayed action by the driver or car owner.
So, if you own the car or your profession or passion is driving, then it is very significant that you should have proper knowledge of what the check engine light is, why it goes on, and what the common reasons are behind this warning. Read this post till the end to know the common reasons behind the engine light on the dashboard.
What Is The Check Engine Light On Meaning, And Why Does It Flash On?
The check engine light is simply a signal that tells drivers that something is wrong with the emission system or that the engine is not working properly. If the light is steady, you can usually drive, but if it is flashing, you can look for serious help from car engine repair shops because a flashing check engine light may indicate serious engine problems.
Never try to ignore the check engine light on because it can lead to higher emissions, poor fuel efficiency, and costly auto engine repair. In general, the check engine light on helps drivers to take timely action to prevent any severe damage, save money, and keep their vehicle in roadworthy condition.
7 Common Reasons Your Car’s Check Engine Light On
1] Faulty or Loose Gas Cap
The most familiar cause is an unfastened, damaged, or missing gas cap, and it can flash the check engine light on. The gas cap is used to seal the fuel system for reduced emissions and to maintain engine pressure. If the fuel system is not tightened properly, then the fuel vapors of the burned fuel leak, and it will affect the performance of the vehicle. Replacing or retightening the rubber gas cap helps you with this problem.
2] Defective Oxygen (O₂) Sensor
The oxygen sensor is placed to monitor the unburnt oxygen in the exhaust system, which regulates the air-fuel mixture. If the oxygen sensor fails, it will trigger the car’s check engine light on and detect more unburnt oxygen in the system, which will flash the car’s check engine light, and it will affect mileage, increase emissions, and affect the catalytic converter. Replacement and scheduling services are the two things that you can do with this issue.
The ignition coil and spark give the initial spark to the air-fuel mixture present in the engine cylinder. If the ignition coil or spark plug is worn out, it will activate the check engine light on, and you will start having poor acceleration and poor mileage.
It might be possible that the vehicle may shake or stumble, and performance may become inconsistent. Replacement of the spark plug every 40,000 to 60,000 km and constantly tracking the ignition coil helps you to increase the lifespan of the ignition system of the vehicle.
4] Malfunctioned Mass Air Flow Sensor
The defective mass air flow sensor is one of the reasons behind the car’s check engine light being on. The mass air flow sensor decides the amount of air that should go to the engine cylinder and regulates the right amount of air for the air-fuel mixture.
If this mass air flow sensor goes faulty, the driver might face rough idling, excess fuel consumption, and poor acceleration. To restore the engine performance, you can replace the sensor, or if it has become dirty, you can clean it and reset the sensor.
5] Catalytic Converter Problems
The fifth reason behind this warning is a defective catalytic converter. The catalytic converter converts the harmful carbon monoxide into less harmful gases, and if these gases are not emitted properly, then the vehicle will have poor fuel economy and reduced power. Scheduled auto care services and replacement of the catalytic converter can help you to restore the car’s performance.
6] Charging system or battery issue
A damaged charging system and wiring system, and a weak battery can trigger the car’s check engine light. In modern days, cars are highly equipped with AI and electrical systems, and batteries can also be the reason behind this warning because any fault can happen at any time.
So, to avoid this problem, scheduled servicing of the vehicle is very important, as during servicing, mechanics will have an eye on the overall condition of the car battery, wiring, and electrical system of the vehicle.
7] Vacuum Leaks
Vacuum leaks happen when air or gases escape from the loose intake components and cracked hoses, and whenever air-fuel imbalances occur, the vehicle will start rough idling, engine stalling, and racing.
Vacuum leaks are one of the reasons behind the warning of the check engine light on, and they can be avoided by scheduled servicing, when mechanics will find the leaked hose or intake components.
Conclusion
The check engine light acts as the driver’s friend and timely informs them about any future danger. Anyone can face danger if he/she passes over the warning signs of the car’s check engine light. Proper scanning of the car with an experienced and professional car engine mechanic in Perth can help you on time when your car’s check engine light is on. These auto care services companies also provide tow truck services Perth, so that if the breakdown happens, they can tow your vehicle to the car engine mechanic Perth. And there, they can diagnose the problem in an early stage and give the right treatment to your car to fix the issue of car check engine light on.
FAQ’s
1. What is the most common reason for the check engine light on?
Answer 1:
A loose gas cap, worn-out spark plugs, and a damaged wiring system are the most common reasons for the check engine light to come on.
2. Can a check engine light come on and nothing be wrong?
Answer 2:
Yes, it is possible sometimes, but it will be an expectation.
3. How much does it usually cost to fix a check engine light?
Answer 3:
The cost to fix a check engine light depends on the reason why this warning is flashing to you.
4. How urgent is a solid check engine light?
Answer 4:
If the check engine light is steady, you can drive and delay 1-2 days, but if the light is flashing, you can contact a car engine mechanic Perth because there is something serious with the engine.
5. Can I still drive if the check engine light is on?
Answer 5:
Yes, only if it is steady, and if it is flashing, get off the road.
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