🛠️ Buderus Central Heating Error Codes: Meanings and Quick Solutions

Your Buderus Logamax central heating system has stopped and is displaying a strange code on the screen? 🧐 Don't worry! These error codes are designed to help you quickly identify the problem, whether it's a simple pressure drop or a component that needs replacing. We've prepared a complete guide for you to help you understand what your central heating system is trying to tell you. 📝

🔍 The Most Common Buderus Error Codes (Logamax U042, U052, GB012, GB172)
Here's what the most common alerts mean and how you can act:

💡 How to Reset a Buderus Central Heating System?
If the error was caused by a temporary fluctuation (gas or electricity), you can try the Reset function. 🔄 Press the Reset button for 2-3 seconds. If the error reappears immediately after starting, it's a sign that a part needs to be checked by a specialist. 👨🔧

⚠️ Safety first! If you smell gas or notice water leaks inside the boiler, immediately turn off the power and contact an authorized service! 🛡️ For permanent repairs, always use original Buderus spare parts.
-A 208 The appliance is in flue gas mode. After 15 minutes, flue gas mode is automatically deactivated

.
H 200 The appliance is in heating mode.
=H 201 The appliance is in hot water production mode.
0A 202 The pulse signal lock is active: the time interval for the burner to restart has not yet been reached (service function 2.3b).
0C 283 The burner is switched on.
0E 265 The heat requirement is lower than the minimum heat output of the appliance. The appliance is operating in on/off mode.
0H 203 The device is ready for operation, there is no heat demand.
0L 284 The gas valve is open, first safety time.
0P The differential pressure switch does not open in the rest position. Check the differential pressure switch and wiring, check the connecting hoses.
0U 270 The device is switched on.
0Y 204 The current flow temperature is higher than the set flow temperature. The device is switched off.
0Y 276 The temperature at the flow temperature sensor is > 95 °C.
This error message can occur without any malfunction if all radiator valves are suddenly closed.
▶ Check the operating pressure of the heating system.
▶ Open the service valves.
▶ Check the heating circuit pump with the service function t03
▶ Check the connection cable of the heating circuit pump.
▶ Turn the heating circuit pump, replace if necessary.
▶ Adjust the pump output or the pump characteristic field accordingly and adapt them to the maximum output.
1A Flue gas outlet at the flow safety device. Check the flue gas path.
1L Flue gas outlet at the combustion chamber. Check the heat exchanger for dirt.
1Y Flue gas temperature sensor not recognised. Check the temperature sensor and the connecting cable for an interruption.
2E The filling pressure of the heating system is too low. Check the filling pressure, top up if necessary.
2E 357 The venting function is active.
2H 358 Blockage protection for 3-way valve active.
2P Temperature gradient too high. Check pump and bypass line.
2P 341 Gradient limitation: Temperature rise too fast in heating mode.
▶ Check the operating pressure of the heating system.
▶ Open the service valves.
▶ Check the heating circuit pump with service function t03
▶ Check the connection cable of the heating circuit pump.
▶ Turn the heating circuit pump, replace if necessary.
▶ Adjust the pump power or the pump characteristic curve accordingly and adapt it to the maximum power.
2P 212 Gradient monitoring for the heating flow has been activated.
2P 341 Gradient limitation: Temperature rise too fast in heating mode.
2P 342 O Gradient limitation: temperature rise too fast in hot water mode.
2Y 281 B Heating circuit pump does not build up pressure.
▶ Check the operating pressure of the heating system.
▶ Open the service valves.
▶ Vent the device with service function 2.2C.
▶ Turn the heating circuit pump on, replace if necessary.
2Y 282 No response to the heating circuit pump speed.
3A Differential pressure switch opened during operation. Check differential pressure switch and wiring, check connecting hoses. Check fan and wiring. Check flue gas pipe.
3A 264 Fan has stopped. ▶ Check the fan cable with plug and replace if necessary.
▶ Check the blower for dirt and blockages and replace if necessary.
3C: 💨 Fan problem. The air pressure switch does not close. There may be a fan failure or a problem with the exhaust kit.

3C 217 The fan does not work. ▶ Check the fan cable with plug and replace if necessary.
▶ Check the fan for dirt and blockages and replace if necessary.
3F 273 The burner and fan have been in continuous operation for 24 hours and are now briefly out of operation for safety checks.
3L 214 The fan is switched off during the safety time.
▶ Check the fan cable with plug and replace if necessary.
▶ Check the fan for dirt and blockages and replace if necessary.
3P 216 Blower running too slowly ▶ Check blower cable with plug and replace if necessary.
▶ Check blower for dirt and blockages and replace if necessary.
3Y Differential pressure sensor does not open when blower is switched off. ▶ Check differential pressure sensor and wiring, check connecting hoses. ▶ Check, clean or repair flue gas system.
4C STB at supply has tripped. Check system pressure, check temperature sensor, check fuse on PCB, ventilate appliance.
4C 224 Heat block temperature limiter or flue gas temperature limiter has tripped.
If the blocking fault persists for a long time, it becomes a shutdown fault.
▶ Check the temperature limiter of the heating block and the connection cable for breaks; replace if necessary.
▶ Check the flue gas temperature limiter and the connection cable for breaks; replace if necessary.
▶ Check the operating pressure of the heating system.
▶ Vent the device using the service function 2.2C.
▶ Adjust the pump output or the pump characteristic field accordingly and adapt it to the maximum output.
▶ Check the heating circuit pump using the service function t03.
▶ Turn the heating circuit pump on, replace if necessary.
▶ Check the heating block on the water side; replace if necessary.
4E Temperature sensor in the combustion chamber not recognised. Check the combustion chamber temperature sensor and the connecting cable for an open circuit.
4U 350, 4U 222 The flow temperature sensor is defective (short circuit).
If the blocking fault persists for a long time, this becomes a closing fault.
▶ Check the temperature sensor and the connecting cable for short circuits and replace if necessary.
4Y 351, 4Y 223 The flow temperature sensor is defective (interruption). If the blocking fault persists for a long time, this becomes a closing fault.
▶ Check the temperature sensor and the connecting cable for an open circuit and replace if necessary.
4Y The flow temperature sensor is defective. Check the temperature sensor and the connecting cable.
5H EMS communication interrupted. Check the connecting cable and the controller.
5H 268 The device is in test mode (test: function test settings).
5L Communication interrupted. ▶ Check the connecting section of the BUS element, replace if necessary. ▶ Check the control unit and replace if necessary.
6A Flame not detected. Is the gas valve open? Check the gas connection pressure, mains connection, ignition electrode and cable, ionisation electrode with cable.
6A 227 Flame not detected. After the 4th ignition test, the blocking fault becomes a closing fault.
▶ Check whether the gas valve is open.
▶ Check the gas connection pressure.
▶ Check the mains connection.
▶ Check the electrode with cable; replace if necessary.
▶ Check the flue gas system and clean or replace if necessary.
▶ Check the gas/air ratio.
▶ For natural gas: check the external gas flow control device and replace if necessary.
▶ Clean the condensate trap outlet.
▶ Remove the non-return valve in the fan mixing system and check for cracks or dirt.
▶ Clean the heat block
▶ Check the gas valve; replace if necessary.
▶ Check the room air-dependent operation of the combustion air connection or the vents.
6C After switching off the gas: Flame is detected. Check the wiring to the gas block and the gas block. Check the ionization electrode.
6C 228 Flame is detected even though the burner is switched off.
▶ Check the electrodes for dirt and replace if necessary.
▶ Check the flue gas system