Buderus Combi Boiler Error Codes If there are interruptions in the operation of the Buderus boiler, do not rush to repair it yourself or call a boiler repairman. To get started, use the built-in self-diagnosis function. The boiler will immediately tell you an error code that will help you localize the problem and find the right way to repair it. IMPORTANT! Any physical intervention in the operation of the boiler should be entrusted to service center employees. Attempts to fix the problem yourself can greatly increase its consequences.
Buderus Boiler Error Code Solutions
Error codes for wall-mounted heating boilers Buderus Logamax
| The code Fault | Working code | Description | |
| -A | 208 | The boiler is in the “chimney sweep” mode. After 15 minutes, the “chimney sweep” mode is automatically deactivated | |
| -H | 200 | The boiler is in heating mode. | |
| =H | 201 | Boiler in DHW mode | |
| 0A | 202 | Cyclic interlock active: the delay time between switching off and switching on the burner has not yet expired (service function 2.3b). | |
| 0A | 305 | Keep warm duration for GB072-24K: keep warm interval hot water has not yet been exhausted (service function 2.3F). | |
| 0C | 283 | The burner turns on | |
| 0E | 265 | The heat demand is less than the minimum heat output of the boiler. The boiler is in operation on-off. | |
| 0H | 203 | The boiler is in a state of readiness, there is no need for heat. | |
| 0L | 284 | The gas valve opens, the first delay time. | |
| 0U | 270 | The boiler starts up. | |
| 0Y | 204 | The actual flow temperature is higher than the set temperature. The boiler is switched off. | |
| 2E | 357 | The venting function is active. | |
| 2H | 358 | Anti-jamming protection for the heating circuit pump and 3-way valve is active. | |
| 2P | 342 | Limitation of gradients: temperature increase too fast in domestic hot water mode. | |
| 5H | 268 | Boiler test by control system | |
| H11 | Defective hot water temperature sensor (GB072-24K) | Disconnect the temperature sensor. Check temperature sensor, replace if defective Check the connecting cable for breaks and short circuits, replace if defective. | |
| 0Y | 276 | Temperature at flow sensor > 95 °C. | This message may appear without a malfunction if all the valves on the radiators suddenly close or after hot water is drawn from the GB072-24K. Check the operating pressure in the heating system. Open the service taps. Connect the heating circuit pump electrically to the BC20 main controller. Check or replace the heating circuit pump. Correctly set the pump power or characteristic curve and adjust to the maximum power. Check for damage or short circuit in the flow temperature sensor and its wires, replace if necessary. |
| 0Y | 359 | High temperature on the hot water temperature sensor | Check the correct position of the temperature sensor Check for damage or short circuit in the temperature sensor and its wire, replace if necessary. Insert the KIM correctly, replace if necessary |
| 2P | 341 | Gradients limitation: too fast temperature rise in heating mode | Check the operating pressure in the heating system. Open the service taps. Connect the heating circuit pump electrically to the BC20 main controller. Check or replace the heating circuit pump. Correctly set the pump power or characteristic curve and adjust to the maximum power. |
| 3A | 264 | Fan not working | Check the fan and its cable with plug, replace if necessary. |
| 3F | 273 | The burner and fan have been running for 24 hours without interruption and are switched off for a short time for safety reasons. | – |
| 4C | 224 | The heat exchanger temperature limiter or the flue gas temperature limiter has tripped | If a blocking fault is present for a long time, then it turns into a locking fault. |
| 4U | 350 | Flow temperature sensor defective (short circuit). | If the fault is present for a long time, the display will show fault code 4U and operating code 222 |
| 4Y | 351 | Flow temperature sensor defective (break). | If the fault is present for a long time, the display will show fault code 4Y and operating code 223 |
| 6A | 227 | The flame was not detected. | After the 4th ignition attempt, the blocking fault turns into a locking one. |
| 6L | 229 | No ionisation signal during burner operation. | The burner restarts. If ignition is unsuccessful, a 6A lockout fault will be displayed, after the 4th ignition attempt, the lockout fault will change to rapier.
|
| 8Y | 232 | The temperature control relay has tripped AT90. | Check the setting of the AT90 temperature monitor. Check the heating control setting. |
| 8Y | 232 | Faulty monitoring relay temperature AT90 | Check for damage or short circuit in the temperature sensor and its wire, replace if necessary. |
| 8Y | 232 | There is no jumper between the terminals of a separate monitoring relay temperature AT90. | If no temperature control relay is connected, install jumper. |
| 8Y | 232 | Temperature control relay blocked The condensate pump is not working. | Unlock the temperature monitor. Check the condensate drain. Replace the condensate pump. |
| EL | 290 | Faulty main regulator BC20 | Replace main regulator BC20. |
| 3C | 217 | The fan is not working. | Check the fan and its cable with plug, replace if necessary. |
| 3L | 214 | The fan has turned off during the delay time. | Check the fan and its cable with plug, replace if necessary. |
| 3P | 216 | The fan is running too slowly. | Check the fan and its cable with plug, replace if necessary. |
| 3Y | 215 | The fan is running too fast. | Check the fan and its cable with plug, replace if necessary. Check the flue gas system, clean or repair if necessary. |
| 4C | 224 | The heat exchanger temperature limiter or the flue gas temperature limiter has tripped. | Check for damage to the temperature limiter of the heat exchanger and its connecting cable, replace if necessary. Check the flue gas temperature limiter and its connecting cable for damage, replace if necessary. Check the operating pressure in the heating system. Check temperature limiter, replace if necessary. Check the pump pressure, replace the pump if necessary. Check fuse, replace if necessary. Vent the boiler. Check the water circuit of the heat exchanger, if replace if necessary. For boilers with a splitter in the heat exchanger, check that a splitter is installed. |
| 4U | 222 | Flow temperature sensor defective (short circuit). | Check for damage or short circuit in the temperature sensor and its wire, replace if necessary. |
| 4Y | 223 | Flow temperature sensor defective (break). | Check for damage or breakage of the temperature sensor and its wire, replace if necessary. |
| 6A | 227 | The flame was not detected. | Check the protective conductor connection. Check that the gas cock is open. Check the gas supply pressure Check the electrical connection. Check electrodes with wires, replace if necessary. Check the flue gas system, clean or repair if necessary. Check the gas-air ratio, correct when need. For natural gas: check gas flow switch, replace if necessary. When working with combustion air intake from a room, check the air supply to the room and the ventilation openings. Clean the drain of the condensate trap Dismantle the membrane in the fan mixer, check for cracks and dirt on it Clean the heat exchanger Check the gas valve, replace if necessary. Insert KIM correctly, replace if necessary. Two-phase network (IT): set a resistance of 2 ohm between PE and N at the connection of the electronic board to the mains. |
| 6C | 228 | Although the boiler is switched off, a flame is detected. | Check electrodes for contamination, replace if necessary. Check the flue gas system, clean or repair if necessary. Check the electronic board for moisture, dry if necessary. |
| 6C | 306 | After turning off the gas supply, a flame was detected. | Check the gas valve, replace if necessary. Clean the condensate trap. Check electrodes and connecting wires, replace if necessary. Check the flue gas system, clean or repair if necessary. |
| 7L | 261 | Time error at first delay time | Replace main regulator BC20. |
| 7L | 280 | Time error when trying to restart | Replace main regulator BC20. |
| 9L | 234 | Faulty coil or connecting wire of the gas fitting | Check wires, replace if necessary. Replace gas valve. |
| 9L | 238 | Faulty gas valve | Check wires, replace if necessary. Replace gas valve. |
| 9P | 239 | KIM is not recognized. | Insert KIM correctly, replace if necessary. |
| EL | 259 | Faulty KIM or BC20 master regulator. | Replace KIM. Replace main regulator BC20. |
Fault codes for gas boilers Buderus
| Malfunction | Possible causes of malfunction | Recommendations |
| The burner does not turn on | Is the heating emergency switch in the On position? | Turn on |
| Is the control system start switch in the On position? | Turn on | |
| Are the circuit breakers ok? | Check their performance, if necessary, replace the defective machine. | |
| Is the boiler water temperature controller connected? | Check and, if necessary, replace defective parts. | |
| Safety temperature limiter connected? | Check and, if necessary, replace defective parts. | |
| Error message from external safety devices (e.g. safety water level monitor)? | The user must check the heating system, rectify the fault and, if necessary, replace the defective device. | |
| Was the flue gas control system activated? | AW 10: Reset the flue gas control system. AW 50: Wait a maximum of 15 minutes. The boiler will turn on automatically if there is a demand for heat. If triggered repeatedly, check the flue gas path and check the function of the flue gas monitoring system. If there is a defect, then replace. | |
| The burner starts and switches to fault. No spark on ignition. | Is there a sound when an ignition spark is generated when the ignition cable is removed? | If not, then: replace the ignition transformer. If yes, then: Replace ignition electrode or ignition burner. |
| Burner starts and switches to fault. | Are all gas shut-off valves open? | Open gas shut-off valves. |
| Natural gas supply pressure > 8 mbar? | If not, then: find the cause and rectify the fault. | |
| Has the air been removed from the pipeline? | Remove air until ignition of the gas is possible. | |
| The burner starts and switches to fault. No ionization current. | N and L connections reversed? | Eliminate the error. |
| Is there voltage between L and PE? | If not, then: Ground the PE, in this case install an isolating transformer. | |
| Poor contact of the ionization wire? | Eliminate the error, in this case, replace the defective part. | |
| Short to ground on the ionization electrode? | ||
| Defective burner control? | ||
| The burner starts and switches to fault. Ionization current < 1.5 mA. | Is the core or ceramic of the ionization electrode dirty? | Clean the ionization electrode, if necessary replace the pilot burner. |
| Boiling sounds | Limescale deposits or scale formation in the boiler? | Clean the water circuit of the heating boiler in accordance with the manufacturer’s recommendations. With constant loss of water, determine and eliminate the cause. If required, carry out water treatment and install a dirt trap |
Fault codes for combined boilers Buderus Logano
| Fault code | Possible causes of malfunction | Recommendations |
| The burner does not turn on | Is the heating emergency switch in the On position? | Turn on |
| Is the control system start switch in the On position? | Turn on | |
| Are the circuit breakers ok? | Check their performance, if necessary, replace the defective machine. | |
| Is the boiler water temperature controller connected? | Check and, if necessary, replace defective parts. | |
| Safety temperature limiter connected? | Check and, if necessary, replace defective parts. | |
| Error message from external safety devices (e.g. safety water level monitor)? | The user must check the heating system, rectify the fault and, if necessary, replace the defective device. | |
| Was the flue gas control system activated? | AW 10: Reset the flue gas control system. AW 50: Wait a maximum of 15 minutes. The boiler will turn on automatically if there is a demand for heat. If triggered repeatedly, check the flue gas path and check the function of the flue gas monitoring system. If there is a defect, then replace. | |
| The burner starts and switches to fault. No spark on ignition. | Is there a sound when an ignition spark is generated when the ignition cable is removed? | If not, then: replace the ignition transformer. If yes, then: Replace ignition electrode or ignition burner. |
| Burner starts and switches to fault. | Are all gas shut-off valves open? | Open gas shut-off valves. |
| Natural gas supply pressure > 8 mbar? | If not, then: find the cause and rectify the fault. | |
| Has the air been removed from the pipeline? | Remove air until ignition of the gas is possible. | |
| The burner starts and switches to fault. No ionization current. | N and L connections reversed? | Eliminate the error. |
| Is there voltage between L and PE? | If not, then: Ground the PE, in this case install an isolating transformer. | |
| Poor contact of the ionization wire? | Eliminate the error, in this case, replace the defective part. | |
| Short to ground on the ionization electrode? | ||
| Defective burner control? | ||
| The burner starts and switches to fault. Ionization current < 1.5 mA. | Is the core or ceramic of the ionization electrode dirty? | Clean the ionization electrode, if necessary replace the pilot burner. |
| Boiling sounds | Lime deposits or lime scale in the boiler? | Clean the water circuit of the heating boiler in accordance with the manufacturer’s recommendations. With constant loss of water, determine and eliminate the cause. If required, carry out water treatment and install a dirt trap |