Failures of gas boilers Daewoo: decryption of error codes + repair recommendations

Vasily Borutsky
Checked by a specialist: Vasily Borutsky
Author: Mikhail Yashin
Last update: December 2019

Failure of any element of the heating system usually completely stops the process of heating the house. The most problematic place in the circuit is the boiler, which consists of many nodes. The complexity of the design makes its repair a difficult task.

However, not everything is so bad, because the malfunctions of Daewoo gas boilers, for example, can be determined almost instantly thanks to a faultlessly functioning display system. Of course, not all problems can be fixed independently, but in some cases you can do without the services of gas workers.

All about decoding error codes that occur during the operation of Korean equipment, you will find in our article. We will talk about how to respond to these self-diagnosis systems. We will show you how to quickly solve the problem and restore heating in full.

Gas boiler series Daewoo

Daewoo is one of the most famous Korean conglomerates that ceased to exist in 1999. Many divisions of the concern gained independence or joined the structure of other companies.

Now in South Korea there are two companies that previously were related to the corporation and produce gas boilers:

  • Altoen Daewoo Co., Ltd (until 2017 - Daewoo Gasboiler Co., Ltd). Now the production facilities are located in Dongtan.
  • Daewoo Electronics Co., a manufacturer of gas equipment at KD Navien's plants.

Components for boilers of both companies are made in South Korea and Japan, and the assembly is carried out in an automated mode.

Production facilities of Daewoo subsidiary
Altoen Daewoo Co., Ltd did not begin to transfer production facilities to Chinese industrial clusters, so as not to lose the possibility of constant quality control of products

The following lines of gas boilers from Altoen Daewoo Co. are represented in Russia Ltd:

  • DGB MCF. Boilers with an open combustion chamber.
  • DGB MSC. Boilers with a closed combustion chamber.
  • DGB MES. Condensing boilers with a closed combustion chamber. The models of this line have a weekly programmer of work, an autonomous control panel, and the connection of the chimney is also simplified.

All models of these lines are wall mounted. bypass, that is, designed for heating and hot water.

Gas boiler control unit Deu
Models of the DGB series are equipped with an informative display on which an error code is displayed if a malfunction occurs or the built-in automatic diagnostic system has worked

Daewoo Electronics Co. There are two ranges of gas boilers: wall mounted “DWB” and floor - “KDB”. They have their own characteristics, including error codes that differ from competitor models. However, these boilers in Russia are not widely used.

Therefore, the article will contain only error codes for gas boilers from Altoen Daewoo Co., Ltd.

Errors and methods for their elimination

The number of automatically detected faults for Daewoo boilers is grouped by 19 events, each of which has its own code. Seeing the display, you can try to solve the problem yourself or give the called wizard a first idea of ​​the problem.

Some malfunctions of gas boilers do not depend on the type of combustion chamber or other features of the equipment. But there are problems that are characteristic only for a certain line. Boilers Daewoo Altoen (Gasboiler) have end-to-end error numbering, and the methods for eliminating them are almost the same for all models.

Error type “E0”

This code indicates an error in the room temperature sensor, which is integrated in the control panel. An example of this malfunction shows that it is far from necessary to call a repair team every time.

It is necessary to disassemble the device, clean the contacts and check the sensor using a tester. If necessary, it must be replaced. If you do not have the skills to disassemble and repair such products, then you can take the remote control to any workshop specializing in electronics.

Error type “E1”

A decrease in pressure in the heating system was recorded. The simplest case leading to this problem is a breakdown of the minimum pressure switch or the absence of a signal between the sensor and the control board. However, first of all, you need to immediately check the heating circuit for leaks.

Leak - the cause of the pressure drop in the heating circuit
Leaking pipes or radiators can occur in places where the presence of water will not be immediately noticeable. This is a floor, storerooms or basement. Therefore, you need to sequentially go around the entire circuit

A coolant leak can occur not only in the circuit, but also in the nodes of the heating equipment, such as:

  • heat exchangers;
  • hydraulic pump;
  • relief valve;
  • feed tap, etc.

In this case, the water system will have to be changed, although sometimes replacing the gaskets may be sufficient.

Also, for some reason, the recharge may be blocked. Although in this case, the issue of leakage also arises, which is gradual.

The pressure drop in the circuit without a coolant leak can occur in the event of a drop pressure in the expansion tank closed type, which is installed in the boiler. In this case, it will have to be repaired.

After eliminating the cause of the leak, it is necessary to fill the circuit with the restoration of the working pressure.

Error type “E2”

The operation of a gas analyzer, signaling about incomplete combustion of the supplied mixture or smoke entering the chimney.

The problem lies in insufficient traction, the cause of which may be:

  • Changing the living section of the flue channel as a result of its pollution. It rarely happens, mainly due to the ingress of a foreign object or small animal. Icing is also possible in the area where the pipe exits. The gas boiler flue must be cleaned.
  • Strong wind support.A difficult case, since it is necessary to re-calculate the geometry of the pipe or install a windproof structure.

There may also be a problem with the fan. Most often, this is the contamination of the blades, which can be seen or violation of rotation, which is easy to hear.

Failures of gas boilers Daewoo: decryption of error codes + repair recommendations
The chimney for the gas boiler has parameters different from the hood of the furnace heating. The fact is that the temperature in the burner of the boiler is relatively small, so the traction force will be less

The problems described above can be determined independently. If the chimney and fan are functioning normally, then there remains the possibility of a sensor breakdown. It will have to be replaced.

Error type “E3”

An error occurs when fixing the fact of overheating coolant. There are two main reasons:

  • malfunction of emergency thermal relay;
  • slowing or stopping the circulation of the coolant.

If such an error occurs, you need to wait until the device cools down, make it zero (turn it off and on) and start again. If the error repeats, then this means that the operation was not false (this happens) and will have to be sorted out.

First of all, it is necessary to determine whether the coolant circulation rate is sufficient. To do this, start the boiler without heating and listen to the pump. His hum should be ordinary.

Problems with this node can be caused by several reasons:

  • Lack of power. You will have to ring the wiring and find a break.
  • There is power, but the pump does not work. You must show it to an electrician. If there is a break in the winding, then it is cheaper to replace the entire assembly. If other wires are broken, the problem can be eliminated and the pump will work again.
  • Jamming of the rotor shaft. Such an event rarely occurs without damage, so it is better to replace the pump.
  • Impeller wear. Need a replacement pump.

It is also possible to disconnect the contacts of the signal wire from the pump to the board or to break the central board itself.

Removing dirt from the coarse filter
Poor coolant circulation can be caused by clogged dirt filter. It needs to be cleaned periodically, but not everyone performs this procedure on time

If the pump is operating at full power, the cause of poor circulation is in the circuit. She may be:

  • Decrease in pressure in the system and failure of the pressure sensor. Rare case.
  • Air congestion. It is necessary to check the entire circuit by letting air through the Majewski taps and similar fittings.
  • Accidental closure of one of the elements of valves. Check all taps and plugs.
  • Clogging. Rare case. A difficult problem, first of all, because of the difficulties associated with finding the place of the mud plug.

If the pump works normally, and the circuit normally passes the coolant, then the temperature sensors must be replaced. Most likely, they failed.

Error type “E4”

This code signals the activation of the pressure switch - the draft sensor in the chimney. The main causes are the same as for the error with the code “E2”.

If the chimney of the gas boiler and the fan are working properly, then the problem may be in the signal from the sensor. First of all, you need to check the connection density of the contacts to the sensor and to the central board, as well as ring the wiring.

Condensation in the tubes or poor connection to the sensor is also possible. Damage to the pressure switch itself is unlikely.

Error type “E5”

Alarm from the flame sensor. If visually when the boiler is turned on and off, the ignition is normal, then the flame sensor must be checked.

First of all, you need to make sure that it is in good contact with the main board (check the connection of the wire and ring it). Also make sure that there is a voltage of 5 volts between the terminals of the CN05 sensor.

Position of shutoff valves for boiler operation
In the absence of ignition, the problem may not be in the boiler. Check the position of the gas shut-off valve first

If the sensor works fine and the ignition does not cause problems, then the error is in the central board.It will have to be replaced.

If you visually manage to detect a problem with the ignition, then you must perform the following steps:

  • Zero the unit and try to ignite again. Perhaps the reason is one of the capacitors or the residual charge on the ignition transformer.
  • Make sure that the maximum and minimum gas pressure is correctly adjusted for the nozzles installed in the device. Regulatory figures can be found in the instruction manual.
  • Inspect the ionization electrode for contamination. Make sure that there is an acceptable clearance between it and the burner. Make sure there is a spark (previously blocking the gas).
  • Perform ignition power adjustment in the service menu. It is necessary to use the parameters that are prescribed in the user manual.
  • Make sure that there is no breakdown on the body (that is, the user does not receive an electric shock when touching the elements of the boiler).
  • Make sure there is no grounding breakage.
  • Check for gas sticking. It is enough to insert a silicone tube into the fitting and press hard.
  • Ring the valve coil open.

If the problem is in the gas valve, then it will have to be changed.

Repair of a gas boiler brand Daewoo
Often a break in the gas valve coil (above) and other electrical problems can be visually recognized or identified by the characteristic smell of burnt wiring

The example of this error shows that sometimes, in order to repair a gas boiler, Daewoo needs knowledge in several areas: electrical, electronics, mechanics. Therefore, with complex errors, it’s still better to call experienced gas service masters, with whom contract signed for the supply of blue fuel and maintenance of units.

Error type “E6”

Gas leakage sensor tripping. If the smell of gas is felt in the boiler room, it is first necessary to close the shut-off valve at the entrance to the house. Then you need to check the gas pipeline (up to the boiler valve) and valves for damage. If they are found, you should contact the gas service.

If the smell of gas is not felt, then after some time you can start the boiler again. It is advisable to be nearby at this time and have a gas analyzer with you. If the sensor is false, then it must be replaced.

Error type “E7”

This code is displayed if the board “lost” the remote control. The problem may be a breakdown of the control panel or the board unit responsible for communication.

Control devices from other Korean manufacturers (Navien, Hydrosta, etc.) are suitable for Daewoo boilers, so there is no particular problem in replacing this part.

Error type “E8”

A break in the connection between the temperature sensor of the heating circuit and the central board. Typically, a problem occurs if the thermistor breaks down. First, of course, you need to see if the contacts have departed, then ring the wiring. If it is working, then the sensor should be replaced.

Temperature sensor for Daewoo boiler repair
You can replace the sensor yourself. All modern measuring devices for this purpose are equipped with special sockets, so you don’t have to solder anything

It is theoretically possible to break the central board unit, although usually in this case it is completely, but not partially malfunctioning.

Error type “E9”

Leakage in the boiler. The water sensor has tripped. It is necessary to open the boiler and see where the fistula formed. There may also be a problem in the gaskets of the nests where the temperature sensors for heating and hot water are installed.

Error like “EA”

Make-up of the circuit water occurs more than 1 time in 5 minutes. This indicates a leak. Its volume is not so significant as to stop the boiler as a result of boiling water or depressurization.

This situation cannot be ignored, since a small leak at any moment can turn into a full-fledged rush with an emergency stop of the boiler and serious consequences for objects in the house.

Error type “EC”

Central control boards are universal for all models within the same line.The error code “EC” indicates an incorrect boiler model selection. This usually happens when replacing the center board or when resetting due to a sudden power outage.

Voltage stabilizer at the input of the mains to the gas boiler
It is customary to install a stabilizer in front of the gas boiler. This avoids breakdowns of expensive electronics and equipment downtime during the heating season.

To solve this problem, just configure the settings using the service menu.

Error like “Ed”

The second letter of this code is the lowercase “d”. Manufacturers have moved away from the template so that users do not confuse the capital “D” and the number “0”, which have similar outlines. The error means that the built-in stabilizer detected a deviation of the current frequency.

If the electricity parameters often deviate from the standard values, the boiler electronics may fail.

Error type “EE”

This code indicates a problem with the smoke exhaust fan. The speed sensor indicates a low value.

The malfunction may be caused by:

  • impeller blockage;
  • impaired shaft lubrication;
  • inaccurate sensor readings.

Also, you cannot rule out a board error, although this option is unlikely.

Error type “EF”

The signal that the three-way valve responsible for switching the water flow has been open for more than 90 minutes. This indicates its jamming. To prevent this damage, it is necessary to install a filter that will prevent clogging.

Three-way valve for boiler repair
The three-way valve is equipped with power wires and a communication loop with the central board. If an “EF” error occurs, first of all you need to ring the wiring and fix the contacts well

The most serious damage is a burnt valve actuator. In this case, the entire distribution unit is best replaced.

Error like “U0”

The flame sensor does not “see” the fire. The problem of ignition. If the flame lights up and goes out, the reason may be the quality of the feed mixture, the gas pressure or the absence of exhaust.

Gas holder for autonomous gas supply
The chemical composition of liquefied gas is different from the main one. For each specific mixture, there is a set of nozzles for the burner. You must not forget to put a suitable kit

If the flame ignites, the auto-ignition electrode continues to click, but the error still remains, then the cause may be a sensor defect or poor connection to the board.

One of the defects of the sensor is just its pollution. If you wipe this part, then often the problem is solved.

Error type “U1”

Buttons on the control panel sunk. This repair does not apply directly to the gas boiler, and any electronics specialist can carry it out. To do this, it is necessary to disconnect the panel from the boiler body and take it for repair.

Error type “U8”

Error in the hot water temperature sensor. The causes of the failure and the necessary actions in this case are similar to the situation with the error “E8”. The boiler does not stop its operation, but functions only in the heating support mode.

During the replacement of the sensor, the boiler will need to be stopped and disconnected from the power supply.

Error type “U9”

The signal from the temperature sensor, which is located in the chimney. The most likely situation is pipe clogging. They must be cleaned. If no contamination is detected, then the problem may be with the defective sensor.

Almost half of the stops of the Daewoo gas boiler are related to problems encountered at other nodes of the heating circuit.

In addition, many boiler malfunctions can be eliminated on their own if there is at least minimal repair skills for any equipment. Therefore, it is necessary to analyze the type of error and only after that make a decision either on the repair on your own, or on the call of specialists.

Conclusions and useful video on the topic

Replacing the Daewoo MSC Series Heat Exchanger:

Determining the type of malfunction associated with the flame ignition electrode:

Instruction of a specialist in working with boilers of the MSC series. Suitable for other rulers Daewoo.Following these guidelines closely prevents many problems from occurring:


It should be remembered that improper handling of flammable gas can lead to an emergency - fire or explosion. Therefore, if there is any doubt about the ability to independently solve the problem, it is necessary to call the craftsmen from the service center or gas service.

Tell us about your experience in identifying and resolving breakdowns of Korean-made gas units. It is possible that your advice will be useful to interested site visitors in solving their problems. Please leave comments in the block below, ask questions and post photos on the topic of the article.

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