Buderus Gas Boiler Error Codes - Shiva Technical

Buderus Gas Boiler Error Codes

buderus gas boiler error codes

-A – The machine is in the “chimney sweep” mode. After 15 minutes, the “chimney sweep” mode is automatically deactivated


-H – Boiler is in heating mode.


(=) H – DHW unit


0A – Clocking active: the delay time has elapsed between the burner shutdown and start (service function 2.3b).


0A – Duration of hot support for GB072-24K: the time interval for maintaining hot water is not yet exhausted (service function 2.3F).


0C – Burner starts


0E – The heat demand is less than the minimum heat output of the boiler. The boiler operates in on-off mode.


0H – The device is in the ready state, there is no need for heat.


0L – Gas fittings open, first delay time.


0U – The boiler starts.


0Y – The actual flow temperature is higher than the set temperature. The boiler switches off.


2E – Error: The deaeration function is active.


2H – The heating pump and the three-way valve are actively protected against jamming.


2P – Gradient limitation: too rapid temp. rise in hot water mode.


5H – Boiler test with control system


H11 – Damage to the DHW temperature sensor (GB072-24K)

Remove the temperature sensor.
Check it, and if it is defective, replace
Check the connecting cable for an open and short circuit, replace if faulty.


0Y – The temperature at the flow sensor is more than 95 ° C.

This message may appear in the absence of a malfunction if all valves on the radiators are suddenly closed or after the hot water is removed from the GB072-24K.
Check the working pressure in the heating system. Open the service valves.
the heating circuit pump Electrical connection to the main controller BC20.
Rotate or replace the heating circuit pump.
Correctly set the power of the pump or its characteristic and reconcile with maximum power.
Check for damaged or short circuit to the flow temp. sensor, replace if necessary.


0Y – High temperature on the hot water temperature sensor

Check the correct position of the sensor.
Check it, and if it is defective, replace
Insert the KIM correctly, replace if necessary.


2P – Gradient limitation: too rapid temp. rise in heating mode

Check the working pressure in the heating system. Open the service valves.
the heating circuit pump Electrical connection to the main controller BC20.
Rotate or replace the heating circuit pump.
Correctly set the power of the pump or its characteristic and reconcile with maximum power.


3A – The fan does not work. Check it, and if it is defective, replace


3F – The burner and fan have been operating for 24 hours without interruption and are switched off for a short time for safety reasons.


4C – The heat exchanger temp. limiter or the limiter of the flue gas temp. of the Buderus boiler has tripped. If the blocking fault exists for a long time, then it goes into a locking Error.


4U – Flow temperature sensor is faulty (short circuit). If the fault persists for a long time, the display shows fault code 4U and operating code 222


4Y – The flow temperature sensor (break) is defective. If the fault exists for a long time, the display shows fault code


4Y and operating code 223


6A – No flame detected. After the 4th ignition attempt, the blocking Error goes into the locking.


6L – No ionisation signal during burner operation. The burner is restarted. If ignition is unsuccessful, the blocking error 6A will be shown, after the 4th ignition attempt the blocking Error goes into fault


8Y – The AT90 temperature monitoring relay has tripped. Check the adjustment of the AT90 temperature monitoring relay. Check the setting of the heating control.


8Y – The temperature monitoring relay AT90 is faulty. Check for damaged or short circuit to the temperature sensor, replace if necessary.


8Y – There is no jumper between the terminals of a separate AT90 temp. monitoring relay.
If the temp. control relay is not connected, then installation a jumper


8Y – Temperature monitoring relay blocked
Unlock the temperature control relay. Check condensate drain.
The condensate pump does not work – Replace the condensate pump.


EL – Defective main controller BC20 – Replace


3C – Error operating the fan. Check the fan and its cable with a plug, replace if necessary.


3L – The fan has shut down during the delay time. Check and, if necessary, replace.


3P – The fan is too slow. Check and, if necessary, replace.


3Y – The fan is running too fast. Check and, if necessary, replace. Check out the flue gas system and clean or repair if necessary.


4C – Error of temperature limiter for heat exchanger or limiter for flue gas temperature.
Check: the presence of damage to the heat exchanger / flue gas temperature limiter and its connecting cable, replace the operating pressure in the heating system, the temperature limiter if necessary, replace the pump head, if necessary replace the pump, fuse, replace if necessary.
Bleed the boiler. Check the water circuit of the heat exchanger, replace if necessary.
For Buderus boilers with a splitter in the heat exchanger, check whether the splitter is installed.


4U – Flow temperature sensor is faulty (short circuit). Check for damaged or short circuit to the temperature sensor, replace if necessary.


4Y – The flow temperature sensor (break) is defective. Check for damage or breakage of the temperature sensor, replace if necessary.


6A – Error: no flame found.
Check: the connection of the protective conductor, the gas tap is open, the gas pressure is being supplied, the connection to the mains, the electrodes with wires, the flue gas

System, if necessary, cleaned or repaired. Check air / gas ratio, correct if necessary. For natural gas: Checkout the gas flow monitoring relay, replace if necessary. When working with the intake of air for combustion from the room, check the room air supply and ventilation opening.
Clean the condensate siphon drain. Remove the diaphragm in the fan mixer, checking for cracks and dirt on it. Clean the boiler exchanger budgers.
Check the gas fitting, replace if necessary. If necessary, apply KIM correctly. Two-Phase Network (IT): Set the resistance between PE and N to 2 ohms when connecting the electronic board to the mains.


6C – In shuting down mode, the boiler registers a flame.
If necessary, check for contamination of the electrode.
If necessary, check flue gas system and clean or repair.
Check the humidity of the electronic board, dry as needed.


6C – A flame was detected after a cut in gas supply.
Check the gas fitting, replace if necessary. Clean the condensate siphon.
If necessary, check the electrode and connecting wires.
If necessary, check flue gas system and clean or repair.


7L – Timing error for first delay time. Replace the main regulator BC20.


7L – Error while trying to restart. Replace the main regulator BC20.


9L – Connecting defective coil or gas fitting wire
Check wiring, replace if necessary. Change the gas fitting.


9L – Defective Gas Fitting
Check wiring, replace if necessary. Change the gas fitting.


9P – KIM not recognized. If necessary, apply KIM correctly.


EL – KIM faulty or main controller BC20. Kim’s place. Replace the main regulator BC20.
Badrus boiler malfunction


1. the burner does not turn on

The emergency switch of the heating system is set to OFF – Enabled.
The start switch of the control system is in the OFF position.
Defective protective equipment – If necessary, to replace the faulty machine, check their operating capacity. Damaged boiler water temperature regulator – check and, if necessary, replace faulty parts. Damaged safety temperature limiter – check and, if necessary, replace faulty parts.

Error messages from external safety devices (such as from safety devices to monitor water level) – the user should check the buderous boiler, repair the fault and replace the element if necessary

The flue gas monitoring system has worked – AW 10: Release the flue gas monitoring system. AW50: Wait for a maximum of 15 minutes. If a request for heat is received, the boiler will turn on automatically. In case of multiple triggers, check the flue gas path and check the efficiency of the flue gas monitoring system. If there is a defect, replace it.


2. The burner starts and switches to fault. There is no spark during ignition.

Does the spark occur when the ignition cable is removed? – If not: Replace the ignition transformer. If yes, replace the ignition electrode or ignition burner.


3. The burner starts and switches on the fault.

All gas shut-off valves are closed – open gas shut-off valves.
The feed pressure of natural gas is more than 8 mbar. If not: Install the cause and repair the malfunction. Is the air drained from the pipeline? – Ventilate the air until the gas releases.


4. Buderus boiler burner starts and switches to a fault. There is no ionization current.

If N and L connections are reconnected, – resolve the error.
What is the voltage between L and PE? – If not: Take out PE grounding, in this case install isolating transformer. Bad ionization wire contact – remove the error, in this case replace the defective part. Small – Repair damage to ground on ionization electrode. Burner Flame Fault – Replace Element.


5. The burner starts and switches on the fault. The ionization current is less than 1.5 mA.

The core or ceramic of the ionization electrode is dirty – if necessary, clean the ionization electrode, replacing the pilot burner.


6. Boiling

Lime deposit or scale formation in the boiler – Clean the boiler’s water circuit according to the manufacturer’s recommendations. With frequent loss of water, establish and eliminate the cause. If necessary, conduct water treatment and install a dirt trap

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