Check Engine Light is on? These are the most common causes

An illuminated check engine light means that the self-diagnostic system in your car's computer has detected an error. After starting the vehicle, it may begin to light up, blink or go out. Check engine light, however, does not necessarily mean a serious failure. It is important to pay attention to the color of the check engine light and other lights. Which might be common or serious causes of warning displays? Be aware that errors indicated by the on-board computer should not be ignored.


What is the check engine light? How does the self-diagnostic system work?

Check engine light is an indicator light that signals errors present or stored in the memory of the car's computer. This feature has all modern cars. Since 2001, all models approved for the European market must be equipped with a self-diagnostic device.  This unit, which includes numerous sensors, continuously monitors, among other things, the operation of the drivetrain and sends information to the central computer. 

Any deviation is the reason for the appearance of the check engine light on the dashboard. In this way, lawmakers care about your safety on the one hand, and the environment on the other. After all, a potential malfunction can not only cause the car to behave incorrectly on the road, but also result in higher combustion or the emission of more pollutants into the atmosphere. In an era of continuous popularization of eco-mobility, this is of vital importance. Therefore, the vast majority of automobiles on the car list have a check engine light.

Keeping in mind that the check engine light is on every car (aside from really old cars), it is worth checking if the control comes on at all when buying a used car. Unfortunately, it is a popular practice among some dishonest sellers to cover the glowing check engine light with non-transparent tape. That is why it is so important to check the operation of all the lights before buying a car.the car

When you turn the key to the first position, all the lights on the dashboard should come on (some for a while, some will stay on until you start the engine). Your concern should be aroused by the absence of the said check engine light - this may mean that the previous owner of the car, unable to remove the fault, simply disconnected or stuck it. It is also a signal that the car may have been involved in a more serious crash and all its consequences have not been eliminated. This, in turn, could result in increased costs of operating the car in the future or lead to it causing an accident.

The check engine light came on. Is it a failure?

When the check engine light comes on while you are driving, you should pull over in a parking lot, turn off and restart the engine. If the check engine light refuses to go out or blinks, it is advisable to go to a nearby service center for diagnosis. 

However, a lit check engine light does not necessarily mean a serious malfunction, so do not panic! If it is a temporary or one-time error that has been caught by the detectors, most likely the check engine light will go off on its own after some time. If it is a matter of a minor error, then the light should no longer come on and you can in theory forget about it. However, if the situation persists (the check engine light will come on for a while and after some time or restarting the engine will go out), then it is better to go to the service center and check the reason for this.

Read also:

Copart or IAAI? What is the best salvage auction site?


Is it OK to drive with check engine light on?

You're probably wondering: can you drive with the check engine light on? The cause of an illuminated check engine light can be a harmless malfunction that you can continue driving with, such as:

- a single ignition misfire,

- too low voltage in the electrical system during startup,

- slimy contacts,

- humidity that has entered the installation,

- incorrect values measured by the sensors (mentioned earlier).


If the check engine light is on for a long time and does not go off after restarting the engine, then it is best to go to a mechanic

Driving with the check engine light on for an extended period of time is not a wise option, even if you do not feel any difference and the engine is running normally and developing full power. This is because you may find that combustion has increased or emissions are higher. Underestimating the warning condition may eventually lead to a more serious breakdown, which will cost you much more to repair.

Immediately to the workshop you should go when, after the check engine light comes on and the engine has gone into the so-called emergency mode. You will then not be able to accelerate to higher speeds, because the engine will not be able to enter higher revolutions. Such symptoms can be a sign of a really serious malfunction.


What causes a check engine light to come on?

More serious reasons for the check engine light being on include:

- failure of the lambda probe,

- failure of one of the ignition coils,

- failure of the injection system,

- damage to the particulate filter,

- damage to the catalytic converter,

- failure of the EGR exhaust gas recirculation valve.


The effects of these malfunctions can range from increased combustion, improper composition of the exhaust gas expelled, poorer performance, to disrupted engine operation leading to failure. The ignition of the check engine light can also be caused by refueling with poor-quality fuel, as well as a poor choice of fuel-air mixture. It may be necessary to replace the flow meter.

Photo by Unsplash