When you are driving on the road and your engine check light comes on, you may panic, not knowing what is wrong and how to solve it. If you pretend not to see it and continue driving, it may cause greater hidden dangers, and you don't know how much it will cost to repair it in a repair shop. Next, this article will answer your doubts.
What is the check engine light?
First of all, we need to understand what the engine fault light is and what it looks like?
The engine fault light (also known as the engine warning light) is an indicator light on the vehicle dashboard, usually with a yellow or orange engine symbol. Its core function is to monitor the working status of the engine and emission system through the ECU (electronic control unit).
When abnormal parameters are detected (such as sensor data exceeding the limit, system logic conflict, etc.), it will automatically light up to remind the driver that there may be a fault.If the Check Engine light is on or flashing continuously, it means that the ECU has stored a fault code and needs further investigation.
The check engine light
Common Reasons:Why the Check Engine Light Comes On
Secondly, we need to know why the engine check light comes on. Knowing the reason for the light will help us not panic or be at a loss when the engine check light suddenly appears on the dashboard. After all, there are only a few possible reasons, and we can find the problem and solve it by checking the vehicle.
Minor or temporary failure:
- The fuel tank cap is not tightened.The seal of the fuel tank cap is affected, causing fuel vapor to leak. When the fuel tank cap is not tightened, the vehicle's evaporative emission system (EVAP) will detect the fuel vapor leak, triggering the engine check light.
The fuel tank cap
- The sensor is false.A slight collision while the vehicle is driving or the engine plug is misactivated may cause a temporary interruption of the ECU signal.This is called a false fault.
Moderate faults requiring prompt repair:
- Emission system problems:
Aging of oxygen sensors.The oxygen sensor generates electrical signals by monitoring the changes in the oxygen content in the exhaust gas. These signals are received by the ECU and used to adjust the fuel injection amount to ensure that the engine operates at the optimal air-fuel ratio.
When the oxygen sensor ages, the data it monitors may be distorted or missing, causing the ECU to be unable to make correct adjustments, thus triggering the engine fault light to light up.
Failure of catalytic converters.The working principle of the catalytic converter is to convert carbon monoxide, hydrocarbons, etc. in the exhaust gas into harmless carbon dioxide, water and nitrogen through oxidation and reduction. When these harmful gases cannot be effectively converted, the exhaust emissions will change, triggering the engine fault light to light up.
Catalytic Converters of Car
- Ignition system failure:
Spark plug carbon deposits.When the spark plug has too much carbon deposits, the working characteristics of the spark plug will be weakened, resulting in poor ignition, which in turn causes the engine fault light to light up.
Ignition coil damage.When the ignition coil is damaged, it cannot generate high-voltage electric sparks normally, causing the engine to fail to ignite normally, which in turn affects the normal operation of the engine and causes the engine fault light to light up.
Serious faults requiring immediate stop:
- If the indicator light flashes or turns red, it indicates a serious fault.
If accompanied by oil and water temperature alarms or severe engine shaking, it may involve mechanical damage such as oil leakage. Continuing to drive may cause the engine to fail or cause an engine fire.
What to Do When the Check Engine Light Comes on
The last and most important part. When faced with the situation of the check engine light on, what should we do? Due to the urgency and complexity of the different causes of the engine light on and the different levels of personal understanding of car maintenance, the measures we take are also different.
Preliminary Judgment
If your engine fault light is always on and there are no other abnormalities, it may be a minor or temporary fault. You can do a preliminary inspection and judgment by taking the following measures:
- Check whether the fuel tank cap is tightened
- Check your engine oil level and quality
- Try to start and shut down the vehicle three times in a row, or turn off the engine, disconnect the negative terminal of the battery, wait for 30 seconds, reconnect it, and try to start again. If the fault light no longer lights up, it means the problem has been solved. This method is only suitable for dealing with false faults.
Professionally Handled
If you have an OBD2 diagnostic scan tool that can read and clear codes, and have some knowledge of car maintenance or are able to solve the problem yourself, you can take the following measures:
- Connect your OBD2 scanner to the vehicle diagnostic port with a data cable
- Reading fault codes
- Determine which module the problem occurs in based on the fault code.For example:
If the diagnostic trouble code P0300 appears, it means that the engine encounters random multi-cylinder misfires during operation. Usually, you need to check the ignition system, including the spark plugs, ignition coils and connecting wires, and replace damaged parts if necessary.
If the diagnostic trouble code P0420 appears, it means that the catalyst is inefficient, blocked or failed. You need to check whether the catalyst is damaged and replace it with a new one if necessary. Check whether the exhaust system is working properly.
Engine fault diagnosis using Autel AL629
- If you have the ability and conditions to repair it yourself, you can repair it yourself. After the repair is completed, use the OBD2 scan tool to clear the fault code and the fault light will go out.
- If you don't have the ability to solve it yourself, find the nearest auto repair shop to handle it. If you already know the cause of the fault, it is difficult for the repair shop to ask you to pay extra fees, which saves time and avoids being cheated.
What should you do if you don't have an OBD2 scanner? In non-emergency situations, if the car can still be driven normally, find the nearest auto repair shop for repair. If the check engine light flashes, accompanied by shaking, smoke, etc., please pull over immediately, turn off the engine, and seek tow truck help.
OBD2 Scanner Recommendations
Simple Handheld Obd2 Scanning Tool
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By understanding what the Check Engine Light is and why it comes on, we can be calmer when it comes on. No matter what causes the Check Engine Light to come on, we should not panic. Follow the instructions in this article to perform the corresponding inspections. If you are sure that you cannot solve it yourself, go to a car repair shop as soon as possible. After all, safety is no small matter.