What causes the engine warning light to come on? Explanation of types, degree of danger, and countermeasures

What causes the engine warning light to come on? Explanation of types, degree of danger, and countermeasures

There are multiple warning lights displayed on the instrument panel of the car, including the engine warning light. It’s usually off, so it doesn’t bother me much, but it’s very important to know what to do in case of an emergency, as the warning light may suddenly come on for some reason.
Therefore, we will explain the causes of the engine warning light, which is one of the most important warning lights, and how to deal with it when it lights up.

What is an engine warning light?

The engine warning light is a yellow (orange) lamp shaped like an engine that lights up when an abnormality is detected in the engine control system . It is also called “engine mark lamp” or “engine check lamp”.

It is located near the speedometer on most car models. If the engine control system is working properly, the light will come on when the engine is started, and will turn off when the engine is finished running.

The type of sensor connected to the engine warning light varies from car to car, but all cars have at least an engine warning light to let you know if something is wrong with the exhaust system or the intake system . Therefore, if the engine warning light illuminates or flashes after starting the engine or while driving, it can be determined that there is something wrong with the car.

What do the warning light colors mean?

In addition to the engine warning light, cars are equipped with multiple warning lights, and they are designed to notify the degree of danger in one of three colors: red, yellow (orange), and green .

Red: Serious condition requiring immediate stop
Yellow (orange): Not as serious as red, but prompt inspection required
Green: Safe condition with no particular problems

Of these, the engine warning light is yellow (orange). In other words, although it is not as urgent as red, it needs to be inspected immediately when it is lit.

The color of the warning light is determined by the international standard (ISO) and is common throughout the world. In other words, the above color scheme is the same for foreign cars.

When does the engine warning light come on?

The check engine light will come on at one of the following two times:

When the engine switch is turned on

All warning lights in the instrument panel light up when the engine switch is turned on. At this time, it is also a mechanism to check whether there is a lamp burnout of each warning light and whether there is an abnormality in the warning system.
If it is confirmed that there is no abnormality, the warning light will turn off. Therefore, there is no need to worry about lighting when the engine switch is turned on.
However, if the warning light does not come on even after turning on the engine switch, consult a dealer or a maintenance shop as soon as possible .

When an abnormality is detected in the engine control system sensor

The engine is equipped with a variety of control sensors that constantly check for any dangers that impede safe driving or performance. If this sensor detects an abnormality, the engine warning light will turn on regardless of whether the vehicle is running or stopped.

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The engine warning light lights up when each sensor detects an abnormality. Drivers must understand what the warning lights mean in order to take appropriate action.
Here, let’s check the role of each major sensor and possible problems when the warning light is lit.

O2 sensor

The O2 sensor is the most common cause of the engine warning light coming on.
The O2 sensor, which measures oxygen concentration, plays a role in maintaining optimal combustion conditions for the vehicle.

・If the
O2 sensor malfunctions, it will not be possible to accurately grasp the combustion state of the engine, which may cause problems such as engine stop, abnormal rotation during idling, and high temperature in the muffler catalyst part. .
It also consumes more fuel, resulting in poorer fuel economy.

Air flow sensor

The airflow sensor measures the amount of air sent into the engine and plays a role in adjusting the amount of fuel injection.

・Possible malfunction due to lighting of the engine warning light
If the air flow sensor fails, there will be a difference between the amount of air measured and the amount of air actually sent to the engine, resulting in inaccurate fuel injection. Therefore, there are many cases where troubles in the engine intake system are caused.
Also, even if the air cleaner and element are dirty due to lack of maintenance, the amount of air sent to the engine is reduced, so proper combustion cannot be achieved and the warning light may come on.

Ignition sensor

The ignition sensor is the sensor responsible for engine ignition control.

・Possible problems with the engine warning light lighting In
recent cars, the ignition timing is controlled by a computer. Therefore, if there is an abnormality in the engine ignition, the engine warning light will illuminate. If the abnormality is left unattended, the engine may stop.

Accelerator Position Sensor (Accelerator Position Sensor)

The accelerator position sensor is a sensor that measures the depression and acceleration of the accelerator.

・Possible malfunctions due to the lighting of the engine warning light
If there is an abnormality in this sensor, it will affect gear shifting and rotation speed, so there is a possibility that trouble will occur during driving itself.
If the warning light comes on, stop the car immediately and ask the dealer to inspect it.

Battery sensor

The battery sensor, as the name suggests, is a sensor that checks the battery operation.

・Possible problems
with the engine warning light lit The engine warning light will turn on if the battery is dead or if there is a connection problem with the battery terminals when replacing the battery.
In addition to the battery sensor abnormality, it may also light up to inform you of the battery life, such as a voltage drop. In that case, you will need to replace the battery.

Other anomalies

In rare cases, the check engine light can also come on for the following reasons:

・Dirty or defective
fuel filler cap If the internal pressure cannot be adjusted due to deterioration or dirt on the fuel filler cap, the engine warning light will turn on.
It may also turn on if the fuel filler cap is not properly closed.

・Tachometer and speedometer
abnormalities If any abnormality occurs in various meters, the engine warning light will turn on. If left unattended, the engine may not start, and a malfunctioning meter will also interfere with driving, so have it checked as soon as possible.

・Abnormalities
in the electrical system Modern cars are equipped with various electrical components other than air conditioners and audio systems, and are equipped with many sensors. Among these sensors, there are cases where the warning light lights up even if the sensor related to driving and safety detects an abnormality.

What to do when the engine warning light comes on

When the engine warning light comes on, you must immediately park your car in a safe place, inspect it, and contact a dealer or repair shop if necessary .
If the engine warning light comes on, take the following actions according to the degree of danger.

Park the car in a safe place and check

If the engine warning light comes on, stop the car in a safe place and check. It is important to move to a safe place such as a parking lot or parking area without panicking and stopping on the shoulder of the road just because the warning light has come on .
Also, avoid driving on highways or driving for long periods of time when the warning light comes on.
If the light comes on while driving on the highway, get off the road as soon as possible and stop in a safe place.

If there is no particular abnormality even after looking at the engine, contact the dealer etc.

Even if the engine warning light comes on while you are away from home, in most cases it is difficult for ordinary drivers to identify the cause.
If you can’t find the cause after checking the car, contact the dealer or maintenance shop and ask for instructions. A professional will use specialized equipment to determine what caused the warning light to come on.
When contacting the company, please be as specific as possible and include the following points :

・When you
noticed the engine warning light:
It is important that the date and time are as detailed as possible. Communicate the exact location so that you can know the distance to the

Resolve the cause of the engine warning light

Once you know what caused your engine warning light to come on, it’s important to fix it as soon as possible.
Even if there are no problems with driving, if the warning light is left on, it not only increases the risk of accidents and breakdowns, but also prevents the car from passing inspection.
Since February 2017, vehicles with certain warning lights illuminated will not pass vehicle inspection.

What is the repair method and cost of sensors?

The inspection and repair methods and cost of the sensors that cause the engine warning light to turn on differ depending on the type of sensor and the contractor you ask.
In general, ask the dealer or a maintenance shop for inspection and repair. Depending on the content of the repair, there are cases where you can ask a car supply store to do it, but since special equipment is required to diagnose the engine warning light, it is safer to leave it to a car dealer or a maintenance shop who are professionals in car maintenance.

What to do if the check engine light comes on and off?

Even if the engine warning light lights up once, there are cases where it goes off when the engine is started again, and cases where it turns on and off repeatedly while driving. Even in such cases, the history of errors can be checked at the dealer or repair shop, so even if there is no problem with driving, it is recommended to have it diagnosed once.

Here, let’s check what to do when the engine warning light goes off and when it flashes.

If the engine warning light goes out

Even if the engine warning light comes on while driving, it often goes out when the engine is turned off and then on again.
In this case, the urgency is low, but if the engine warning light has come on even once, there is a possibility that something is wrong. Just in case, let’s have it inspected at the dealer or repair shop as soon as possible.

If the engine warning light flashes

Wiring problems and failure of internal parts can be considered as the cause of the engine warning light flashing on and off.