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Why Is My Check Engine Light On?

Many of us have encountered such a problem as turning on the engine icon (Check engine), the appearance of which scares car drivers. We offer you the five most common reasons why an engine check lights up on the dashboard.

The appearance of the engine indication icon occurs, as a rule, without warning. The reason for the presence of the Check engine cannot be immediately understood. As an option, you can use the ELM 327 scanner to diagnose your vehicle by yourself.

Can I drive with Check Engine light on?

It is ok to drive the car, but please observe it's behavior. Keep on eye on your car's systems such as oil pressure and temperature. If any of them go below normal, immediately stop the vehicle and stop the engine.

Can Check Engine indicator turn off itself?

Yes! If the problem disappears, it will turn off after 50-100 miles driving. Internal electronics will understand that the problem is gone and turn it off. But you should check your car's instruction as this may vary from car to car.

What to do if Check Engine Indicator Light is On?

For most drivers, the appearance of this warning icon on the instrument panel means the need to urgently go to the repair shop to diagnose and eliminate the reason why the warning sign "Engine Check" appeared. But, in most cases, when the "Check" indication appears, you can independently diagnose the cause of the engine failure and, in some cases, possibly eliminate the cause yourself without going to a car service, which will save you money.

1. Replace oxygen sensor (lambda sensor)

The oxygen sensor in your car is part of an exhaust system that monitors how much oxygen is not burnt in the engine's combustion chamber. This sensor helps to control the fuel consumption of the car. A malfunctioning oxygen sensor (lambda probe) means that the car computer is not receiving the correct data, which can significantly increase fuel consumption and reduce engine power. Most cars have 2 to 4 oxygen sensors. If you have a home-based car error scanner, then by connecting it to the vehicle, you can easily find out which sensor needs to be replaced.

For what reason the oxygen sensor in the car becomes unusable: Over time, the sensor becomes covered with a layer of waste and engine oil (oil soot), which reduces the accuracy of reading the sensor to control the gasoline mixture and distribute the optimal fuel consumption. A malfunction of the oxygen sensor in the car leads not only to increased fuel consumption but also to an increased content of harmful CO2 substances in the exhaust.

What you need to do: If you do not change the faulty automobile oxygen sensor, this can lead to failure of the catalyst of your car (it may burst), which will result in expensive repairs. The cost of new catalysts is very high due to the content of precious alloys in them. On some cars, there are several catalysts, the cost of which can reach up to 2000$. So do not pull with replacing the sensor. Although the replacement of the sensor and its price is not very small, it is incommensurable with the cost of the exhaust gas after-treatment system. You can also save on replacement by doing it yourself. Many car manuals have detailed instructions on how to replace the oxygen sensor yourself. If you know where the oxygen sensor is, then it will not be difficult for you to disconnect the faulty "lambda probe" and replace it with a new one. Remember that pulling with the replacement of this critical element must not be pulled!

2. Check a fuel tank cover

Many drivers, in most cases, when the "engine check" indication appears, will think about severe problems in the car engine. Still, they won't even remember to check the fuel system for leaks, which could be broken due to a defect or an insufficiently tightened fuel filler cap. The open or damaged fuel tank cover is a widespread reason for the appearance of the "Check" engine icon.

The cause of the error: Leakage in the fuel system due to air leakage and the filler cap on the fuel tank will increase the fuel consumption of the vehicle, which will cause the engine diagnostic system to display an engine error by turning on the "Check Engine" indicator on the vehicle's instrument panel.

What you need to do: If, when the "Check" indication appears, your car has not lost power, and there are no sound signs of engine damage (knocking in the engine, hum, creaking, etc.), then first check the gas tank for leaks. Your gas tank cap may be cracked or loose. If the cover was not tightened enough, then stretching it to the end, continue on the car for a while to see if the engine error disappears. To prevent the appearance of an engine check for this reason, regularly check the fuel filler cap. Remember that periodically the cover must be replaced with a new one!

3. Check Car exhaust catalyst

An automotive catalyst helps an automobile make its engine exhaust more environmentally friendly. It converts carbon monoxide and other harmful substances into harmless compounds. If your exhaust gas catalyst has become unusable, you will notice this not only when the engine icon (check) appears, but long before that, when the car's power drops two times. For example, when you press the gas pedal, the vehicle, as before, will not have excellent acceleration dynamics.

Because of what the automobile catalyst may fail: if you regularly service your car, following the maintenance regulations of the automobile company, then the catalyst should not fail. The main reason for the failure of the catalyst is the untimely replacement of the faulty oxygen sensor, as well as the non-regular replacement of the spark plugs at the expiration date. When the oxygen sensor or spark plugs are broken, the conversion of carbon monoxide in the catalyst into harmless chemical elements ceases, which leads to overheating of the catalyst, which may fail.

What you need to do: If your catalyst has deteriorated, then you cannot drive a car, as the engine will not work correctly, warning about this by indicating the engine icon (check) on the dashboard. Also, your fuel consumption will be significantly increased, and there will be no engine thrust. Although replacing the catalyst is a costly repair, there is no escape from the repair. Although there is an alternative to replacing the catalyst with a flame arrester, this is not a 100 percent option. Unfortunately, if you are not an experienced auto mechanic, you cannot replace a defective exhaust catalyst yourself. In any case, you will have to contact the auto repair shop. Remember that timely replacement of oxygen sensors and spark plugs protects your catalyst from damage!

4. Replace the air mass flow sensor.

The mass airflow sensor controls how much air must be added to the gasoline mixture for optimal ignition of the fuel. The sensor continually informs the car computer about the amount of oxygen supplied. A defective mass airflow sensor increases fuel consumption, increases the level of CO2 in the exhaust gas, and also reduces engine power and smoothness. Also, with a faulty sensor, poor acceleration dynamics are observed. In cold weather, a car with a faulty sensor will not start well.

What are the reasons for the failure of the mass airflow sensor: Most sensor failures occur due to improper installation of the air filter during its scheduled replacement. Also, if you do not regularly change the air filter, as required by the vehicle maintenance regulations recommended by the manufacturer, the mass airflow sensor may fail.

What you need to do: Theoretically, you can ride for a long time with a broken mass airflow sensor (several weeks or months). But you will notice that the longer you drive, the more fuel consumption increases. Replacing the sensor in a car service is not so expensive since the work itself does not take much time and is quite simple. The main expenses are related to the cost of the sensor, which for some car models can be $100 - $300 if it is an original sensor or up to $100 if an analog substitute. The Self-replacement of the sensor is very simple. You can easily replace it by your self to avoid additional costs. Remember that it is necessary to regularly change the air filter, observing the vehicle maintenance regulations!

5. Replacing spark plugs and high voltage wires

Spark plugs in the car are the main parts for igniting the fuel mixture. If the spark plugs are faulty, the spark is not supplied correctly to ignite the gasoline mixture. In the case of faulty spark plugs, there is often a lack of spark or an incorrect spark supply interval, which affects engine malfunction. If the candles work incorrectly during acceleration, especially from a place, you may feel slight jolts.

What are the reasons for the failure of the spark plugs: Most spark plugs in cars before 1996 must be replaced every 25,000-30,000 kilometers. In newer cars, spark plugs serve more than 150,000 km. However, these deadlines for the scheduled replacement of spark plugs can be reduced due to various factors related to fuel quality and driving style.

What you need to do: If your candles have not changed for a long time, or if you feel the engine's failures associated with ignition, you must immediately replace them with new ones. Do not try to save on untimely replacement of spark plugs, as the cost of spark plugs is not very expensive, as well as the work of replacing them. By changing old spark plugs, you will improve engine performance and reduce car fuel consumption. Changing spark plugs on your own is easy enough. Mostly they are easily accessible under the hood of the car. You need an ordinary candle key to unscrew the candles from the engine. It is also advisable to monitor the condition of high-voltage wires, as over time they can become unusable and pass electricity that is transmitted to the spark plugs, which will reduce the power of the spark. Remember that regular replacement of spark plugs, following the maintenance schedule of your car, keeps your exhaust gas catalyst from breakdowns and also improves engine performance!