What to do if the “Check Engine” light on the car dashboard lit up

Check Engine

Translation of the expression “check engine” in Russian literally sounds like “check engine”. A “check” icon is on the dashboard of most modern cars, but its meaning for many remains unclear. Therefore, if this icon – yellow or orange engine icon – appears and does not disappear (or simply blinks), an inexperienced driver has a natural question: “what does it mean?” Next, let’s try to figure out the reasons why the check engine lights up on the dashboard of your car, as well as how to get rid of it.

Initially, this light gave to know about problems with the carburetor, but now that cars are equipped with full-fledged onboard computers, the message can indicate various malfunctions. For example, a “check engine” error can report problems with the quality of the fuel-air mixture or ignition malfunctions, as well as many other things. The messages can be caused by non-serious breakdowns as well as critical ones.

Thus, when the “check engine” lights up, it is clear only that the ECU has detected a malfunction in one of the systems of the car. Only diagnostics can give a full picture. Below we will consider the main reasons why the check engine light is on and what you need to do about it.

Top 10 reasons why the check engine light comes on

1. Fuel tank cap is open . Check if it is tightly closed.
2. Bad gasoline . The system may be reacting to the quality of the fuel. The solution is to drain the gasoline and refill with better quality gasoline.
3. Oil level . First of all, check its level with a dipstick. Also look for cracks in the block and oil leaks.
4. Problems with the gasoline pump or the screen in the tank. Check to see if the pump is running smoothly, and if it is making any unusual noises.
5. Dirty injectors . Remedy by cleaning the injectors.
6. High voltage wires or coils malfunction.
7. Problem with spark plugs . The icon also lights up when there is a problem with the spark plugs. It is worth checking the serviceability of the plugs and, if necessary, replace them. in one of the cylinders.
8. The lambda probe is defective . The problem can only be solved by replacing this unit with a new one or installing a cheat sheet, cleaning occasionally helps.
9. Catalyst failure . Also solved by replacing the catalytic converter.

Here are only the main causes and solutions. In fact, there are many more. Diagnostics of the onboard computer, which controls all systems of the car, can give a more complete picture of the situation.

Check engine is not hiding on the dashboard of the Madza CX-5

Check engine on the dashboard of Peugeot Partner is hiding in the left corner

How to remove a check engine

Let’s consider in detail those steps, which should be undertaken first of all in order to get rid of the illuminated indicator Check Engine. The algorithm of priority actions is as follows:

1. Check whether the cap is closed. The situation is especially relevant if you have just left the gas station, and soon after that the check engine light came on. This means that either the fuel system is leaking because the cap is not screwed on tightly enough or the fuel quality leaves much to be desired.
2. Check the condition of the spark plugs. To do this, unscrew them and visually assess their condition. Very often it is the spark plugs that activate the Check Engine light. In particular, the reason may be that they start to leak current due to fouling of the electrodes. Such fouling is formed as a result of the high content of metals or other conductive substances in the fuel. Also, an error may occur if the gap between the electrodes on the plug exceeds the distance of 1,3 mm. Separately about the diagnosis of plugs and how to perform it by their color we consider separately. You will also find it useful to know how to replace them.
3. Oil level. If the check engine icon lights up only when the engine heats up, stop and listen, you may hear some unusual engine sounds. Use a dipstick to check the oil level in the engine, and top up if necessary. Also check for oil leaks.
4. If your car is equipped with sensors of technological fluids purity (engine oil, fuel and so on), the indicator may light up if the corresponding indicators exceed the permissible norm. The solution is to replace the relevant filters or completely replace the fluids in case they do not meet the standards.
5. Reset the minus terminal of the battery (15. 20 seconds). After that the Check Engine light should go off and the clock on the computer should reset. This method may be relevant in two cases. The first is a trivial “glitch” ECU. The second – if the memory of the electronic unit has accumulated a large number of small errors, which have not been reset. (as a rule they are caused by usage of low-quality petrol, presence of harmful impurities in fuel-air mixture, moisture on electric contacts and so on).

The most convenient way is not to reset the terminal, so all the settings in the car are reset, but to use a multimode scanner, such as Rokodil ScanX. Because it is an inexpensive version that has compatibility with 99% of vehicles from 1993 year, and it fully supports all the functionality of the popular diagnostic programs for smartphones. Whichever unit has the error, you will not only reset it, but also see the approximate cause.

If after performing the listed actions, the Check Engine indicator did not go out, or went out, but soon lit up again, it means that the error lies deeper, and to eliminate it you need to conduct additional detailed diagnostics with more serious means.

Check engine lights up – what should I do next?

You can try to find out the cause yourself by counting the number of flashes of the check, and check the technical documentation for the designation of such an error code. There are different intervals between flashes for different cars and different codes by which they are interpreted.

Most errors reported to you by the indicator are not critical . It is possible to perform diagnostics in two ways – independently and by visiting a service station. The fact is that to obtain information in this case requires special equipment or at least software for your smartphone.

But first of all it is necessary to find out how the behavior of the car has changed after the appearance of the error. This is done in order to determine whether you can drive with a check engine glowing on the panel, or it is better not to do so, so as not to aggravate the problem.

• RPMs are floating;
• Shaking of the engine;
• Smell of burning is heard;
• Other changes.

• Coolant light;
• Engine overheating;
• Oil light bulb;
• Catalyst icon.

When does the check engine light up?

Finding out the reason why the check light is on

The error code can be read with a laptop with special software. The computer is connected to the ECU of the car by means of a cable and carries out the diagnostics. Also with the help of a laptop you can make additional external commands to the ECU or correct (reset) the errors that appeared.

A simpler method is to download the program for ECU communication and analysis to your Android-based smartphone (for example, TORQUE, it has free and paid versions). And you connect a Bluetooth adapter (autoscanner) to the ECU, which allows you to read information from the device. If you do not have a laptop or you simply do not want to bother installing additional software, you can delegate the described procedures to the employees of the service station. They have all the necessary equipment and programs.

Remember, each car (and sometimes each ECU on the same cars, but of different model years) has a different list of decoding errors. Therefore, after getting the information, it is imperative that you have a standard set of diagnostic trouble codes (Diagnostic Trouble Code – DTC). You can find it in additional diagnostic literature or on the Internet (e.g., on thematic forums dedicated to your car model).

Another common cause for injector engines is injector problems. In particular, the appearance of a significant amount of sludge on them. The solution to such a problem is to clean the injectors. If there are problems with the plugs, injectors, as well as the activated check-engine indicator, there may be the following symptoms:

• weak engine traction;
• high fuel consumption;
• jerking when picking up speed or unstable engine operation;
• “floating” engine rpm at idle.

The next step is to check pressure in fuel system. You should use pressure gauge for this purpose. Standard pressure for the majority of non-tuned cars is 3 atm (kgf/cm2). However, check this information in the technical certificate of your car. If the pressure is much lower, the problem might be a faulty gasoline pump or dirty injectors. If the pressure is low all the time – check the gasoline pump. If it is normal at first, but drops shortly after you start the engine – check the injectors. Also pay attention to the mesh in the gas tank.

It is also worth checking the insulation of the high-voltage wires . It is better to do this not visually, but with a tester turned on to ohmmeter mode. The minimum wire insulation value should not be less than 0.5 megohms . Otherwise, the wire must be replaced.

If the Check Engine light glows after turning the key, and after a few seconds goes out, it means that the system performs self-diagnostics, and there is no reason to worry.

How to get to the service station when the Check Engine light is on

When driving to the service station, try to respect the gentle driving mode. In particular:

• do not exceed a speed of more than 60 km/h;
• do not exceed engine speed over 2500 rpm;
• turn off the air conditioner (heater), multimedia system and other unnecessary equipment that creates additional load on the engine;
• avoid sudden starts and braking, drive smoothly.

You may return to a normal driving mode only after diagnostics and elimination of detected errors.

In lieu of a conclusion

Remember that you should not panic if the Check Engine light is illuminated. In most cases, the causes of its activation are not critical. However, it is necessary to perform a primary diagnosis, consisting of the 5 steps listed above. Also check if the car’s behavior on the road has changed and if other indicators are lit additionally. If minor faults are detected, they must be corrected. If Check Engine is not extinguished after that, then carry out additional diagnostics with the help of an electronic device. It will give you an error code, indicating the cause of the breakdown.

Car mechanic with 20 years of experience in repairing and servicing cars of different brands. Main area: diagnostics and mechanics.

If the check engine lit up: 5 most common reasons for the inclusion of the “Check engine” indication

Many of us have probably faced such a problem as the inclusion of the engine icon indication (“Check engine. “), the appearance of which on the dashboard of the car frightens drivers. Today we offer you to get acquainted with the five (5) most common reasons why the check engine lights up on the dashboard.

The appearance of the engine indication icon on the dashboard occurs as a rule, without warning. The cause of the appearance of this “Check engine” is not possible to understand at once. Even with the presence in the car auto diagnostics (for example, in such cars as, BMW, Audi, Porsche, Mercedes-Benz, VW) that scans all systems of the car for errors and their presence, displaying on the dashboard decoding information, such causes of the appearance of the “check engine” will not be deciphered.

For most drivers, the appearance of this warning icon on the dashboard means the need to urgently go to an auto repair shop for diagnosis and to eliminate the cause for which the warning icon “Check Engine” appeared. But in fact, in most cases, when the “Check” indicator appears, you can independently diagnose the cause of engine malfunction, and in some cases it is even possible to eliminate this cause yourself without a trip to the car service center, which will certainly save you money.

1. Replace the oxygen sensor (lambda probe)

The oxygen sensor in your vehicle is part of the exhaust system which controls how much oxygen is unburned in the engine combustion chamber. This sensor helps control your car’s fuel consumption. Faulty oxygen sensor (lambda probe) means car computer receives wrong data and may considerably increase fuel consumption and reduce engine power. Most vehicles have 2 to 4 oxygen sensors. If you have a home car error scanner, plugging it into your car will allow you to easily find out which sensor needs to be replaced.

Why does the oxygen sensor in your vehicle fail: -Over time, the sensor is covered with a layer of waste and normal engine oil (oil soot), which reduces the accuracy of the sensor readings for gasoline mixture control and optimal fuel consumption distribution. Faulty oxygen sensor in the car leads not only to increased fuel consumption, but also to an increased content of harmful substances CO2 in the exhaust.

What you need to do: -If you do not replace a faulty car oxygen sensor, it may cause the car’s catalytic converter to fail (it may burst), which will cost you an expensive repair. The cost of new catalytic converters because of the precious alloys they contain is very high. Some cars have several catalysts at a time and the cost can be up to 90,000 rubles. So, gentlemen, do not delay with replacing the oxygen sensor. Although the replacement of the sensor itself and its cost is decent, but it is still not commensurate with the cost of the exhaust catalyst system. You can save money on replacing this sensor by doing it yourself. There are detailed instructions in many owner’s manuals on how to replace the oxygen sensor. If you know where the oxygen sensor is located, it shouldn’t be too difficult to disconnect the faulty “lambda probe” and replace it with a new one. Remember that you can not procrastinate with the replacement of this important element!

2. Check the fuel filler cap

Many drivers in some cases when the “check engine” indication appears, they start thinking about serious engine problems, they don’t even think to check the tightness of the fuel system, which may be compromised by a defective or insufficiently tightened fuel tank neck cap. This is a very common cause in the appearance of the engine “Check ” icon.

The cause of the error is: -Tightness of the fuel system due to leaking air from the fuel filler cap, as well as increased fuel consumption of the car, for which the diagnostic system of the car will certainly show an engine error, including the “Check engine” indication on the dashboard of the car.

What you should do: -If your car has not lost its power and there are no sound signs of engine damage (knock, rumble, squeak, etc. in the engine), first of all you should check tightness of the fuel tank. Your gas tank cap may be cracked or not tightened enough. If the tank cap was not tight enough, you can continue driving your car for a while, then look at the dashboard and see if the engine error disappears. To prevent the check engine indication from appearing and lighting up, check the fuel filler cap regularly. Also remember to replace the cap periodically with a new one!

3. Vehicle Exhaust Catalyst

A car catalytic converter helps the car make that engine exhaust more environmentally friendly. It converts carbon monoxide and other harmful substances into harmless compounds. If your exhaust catalyst has gone bad, you’ll notice it not only when the engine “check” icon appears, but long before your car’s horsepower drops by half. For example, when you press the accelerator pedal, your car will not have good dynamics of acceleration as before.

If you regularly service your car in accordance with your car company’s maintenance schedule, the catalytic converter in your car should not fail. The main cause of catalytic converter failure is untimely replacement of a faulty oxygen sensor, as well as irregular spark plug replacements at the end of their useful life. When the oxygen sensor or spark plugs are out of order, the conversion of carbon monoxide in the catalytic converter into harmless chemical elements stops, and this leads to overheating of the catalytic converter, which can lead to catalytic converter failure.

What needs to be done: – If your catalytic converter is out of order, you can not drive your car, as the engine in the car will not run properly, warning of this indication on the dashboard with the engine icon – “check”. Also you will have a very high fuel consumption in your car and you will have no engine traction. Although replacing the catalytic converter is an expensive repair, you can’t avoid it. Although there is an alternative to replacing the catalytic converter with a flame catalytic converter, it’s not a 100% option. Unfortunately of many, if you are not an experienced mechanic, you will not be able to replace the faulty catalytic converter on your own. You will have to go to an auto repair shop anyway. Remember friends that timely replacement of oxygen sensors and spark plugs protects your catalytic converter from breakage!

4. Replace the mass air flow sensor

The mass air flow sensor regulates the amount of air that needs to be added to the gasoline mixture for optimum fuel ignition. This sensor constantly reports data to the vehicle’s computer about the amount of oxygen delivered. A faulty mass air flow sensor increases this fuel consumption, and also increases the CO2 level in the exhaust gas, thereby reducing engine power and smooth running. Also with a faulty sensor, poor acceleration dynamics are observed. In cold weather the car with a faulty sensor does not start well.

Most of these sensor failures occur due to improper installation of the air filter during its scheduled replacement. Also, if the air filter is not changed regularly as required by the vehicle manufacturer’s recommended maintenance schedule, the mass airflow sensor can fail.

What you should do: -Theoretically you can of course drive with a broken air mass flow sensor for a long time (a few weeks or months). But you will soon notice that the longer you drive, the higher your fuel consumption increases. Replacement of the sensor at the car service center is not expensive, since this work is not time-consuming and is simple enough. Its main expense is connected with the cost of the sensor which for some models of cars can cost from 11.000 – up to 14.000 thousand rubles if it is an original sensor, or up to 6.000 rubles if it is an analog substitute. Self replacement of the sensor is very simple. But, in connection with small cost of the work on replacement of the sensor you can entrust this work and an ordinary mechanic at an auto service center. Remember, friends, that it is necessary to change the air filter regularly observing the established maintenance schedule for the car!

5. Replacement of spark plugs and high-voltage wires

The spark plugs in the vehicle are the main parts; they are designed to ignite the fuel mixture. If the spark plugs are defective, the spark is not properly supplied to ignite the gasoline mixture. Faulty spark plugs often have a missing spark or an improper interval of that spark, and this affects improper engine operation. If the spark plugs are not working properly, you may feel a slight jolt while accelerating the car, especially when starting from a place.

What are the causes of spark plug failure: -Most spark plugs in cars before 1996 must be changed every 25,000 to 30,000 thousand kilometers . In newer vehicles, these spark plugs last for more than 150,000 thousand kilometers. But, nevertheless, these terms of planned replacement of spark plugs can also decrease due to various factors, which are naturally associated with the quality of fuel, and driving style.

What you need to do: -If your spark plugs have not been changed for a long time or you feel the lags in the engine operation, which are specifically related to the ignition, you should immediately, without delay replace them with new ones. Don’t try to save money on not replacing your spark plugs on time, as the cost of the plugs themselves is not as expensive as the work of replacing them. By replacing your old spark plugs with new ones, you will improve your engine’s performance and reduce your car’s fuel consumption. Changing the spark plugs in your car is easy enough on your own. Basically, they are all easily accessible under the hood of the car. You will only need an ordinary spark plug wrench to unscrew the plugs from the engine. Also, it is advisable to keep an eye on the condition of the high-voltage wires as well, because over time they can fail and leak electricity that is transmitted to the spark plugs, which can reduce spark strength. Remember that regularly replacing the spark plugs according to your vehicle’s maintenance schedule keeps your exhaust catalyst from breaking down, and at the same time improves the performance of the engine itself!

This article of ours was originally published in 2013, and has been updated with new information since February 17, 2020.