De Dietrich Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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A01
Boiler locks out, burner does not ignite, red fault LED on, display shows A01
Ignition Failure / No Flame Detection
A02
Boiler attempts to start but shuts down quickly, display shows A02, sometimes with short ignition noise
Flame Loss During Operation
A03
Boiler locks out with A03, fan may run briefly, no ignition sequence
Flue Gas Safety / Combustion Fault
A04
Boiler shows A04 and will not start, sometimes after power interruption
Control Board / Configuration Fault
A05
Boiler displays A05 and stops, often after overheating or poor circulation
Overheat Lockout / Safety Thermostat Tripped
A06
Boiler shows A06, fan may run but ignition does not start
Air Pressure Switch / Fan Proving Fault
A07
Boiler displays A07, intermittent lockouts especially in windy conditions
Flame Detection / Ionisation Fault (Intermittent)
A08
Boiler shows A08 and stops, often after a few minutes of operation
Flue Gas Temperature Too High
A09
Boiler displays A09, no heating or hot water, fan may not start
Fan / Air Flow Fault
A10
Boiler shows A10, will not start, sometimes after wiring changes
External Control / Thermostat Fault
A11
Boiler displays A11, intermittent operation, sometimes linked to DHW demand
Flow Sensor / Turbine Fault (DHW)
A12
Boiler shows A12, no heating, pump may run briefly then stop
Flow Switch / Minimum Flow Fault (Heating Circuit)
A13
Boiler displays A13, often associated with low system pressure or recent draining
Low Water Pressure Lockout
A14
Boiler shows A14, pressure gauge high, safety valve may drip
High System Pressure / Overpressure
A15
Boiler displays A15, no heating, pump may run continuously
NTC Sensor Fault – Flow Temperature
A16
Boiler shows A16, DHW temperature unstable or no hot water
NTC Sensor Fault – DHW Temperature
A17
Boiler displays A17, burner stops, pump may continue to run
Return Temperature Sensor Fault
A18
Boiler shows A18, no operation, sometimes after power surge
Internal Communication Error (PCB to Display/Module)
A19
Boiler displays A19, burner output limited or locked out
Gas Valve Modulation / Calibration Fault
A20
Boiler shows A20, no heating, pump may run, burner off
Pump Fault / No Circulation
A21
Boiler displays A21, frequent short cycling, poor temperature control
Outdoor Sensor / Weather Compensation Fault
A22
Boiler shows A22, DHW priority not working correctly, heating locked out
3-Way Diverter Valve Position Fault
A23
Boiler displays A23, no response to user interface, buttons not working
User Interface / Display Board Fault
A24
Boiler shows A24, burner stops, error often appears at high output
Primary Heat Exchanger Overheat / Flow Restriction
A25
Boiler displays A25, burner output limited, sometimes with noisy combustion
Condensate System / Siphon Fault
Symptom
Boiler condensate pipe dripping heavily or gurgling noises from condensate trap
Condensate Drainage Issue
Symptom
Boiler cycles on and off rapidly, room temperature unstable
Short Cycling / Control Misconfiguration
Symptom
Boiler display works but no response to heating or hot water demand
Control Input / Safety Chain Open
Symptom
Boiler does not start at all, no display or lights
No Power / Electrical Supply Fault
Symptom
Boiler emits smell of gas or combustion fumes
Gas Leak / Flue Gas Leakage
Symptom
Boiler fan runs continuously even when there is no heat demand
Fan Overrun / Control Fault
Symptom
Boiler frequently loses pressure and needs topping up
Chronic Pressure Loss
Symptom
Boiler ignites with a loud bang or popping noise
Delayed Ignition / Poor Combustion Setup
Symptom
Boiler leaking water from underneath the casing
Internal Water Leak
Symptom
Boiler makes loud banging or kettling noises during operation
Kettling / Localised Boiling in Heat Exchanger
Symptom
Boiler produces hot water but no central heating
Heating Circuit Demand / Diverter Fault
Symptom
Boiler room or casing excessively hot to touch during operation
Overheating / Poor Ventilation or Insulation Fault
Symptom
Boiler runs but produces no domestic hot water (combi or system with cylinder)
No Domestic Hot Water Production
Symptom
Radiators not heating properly while boiler appears to run normally
Poor Heat Distribution / Circulation Fault
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A01 |
Boiler locks out, burner does not ignite, red fault LED on, display shows A01
|
Ignition Failure / No Flame Detection | View Details |
| A02 |
Boiler attempts to start but shuts down quickly, display shows A02, sometimes with short ignition noise
|
Flame Loss During Operation | View Details |
| A03 |
Boiler locks out with A03, fan may run briefly, no ignition sequence
|
Flue Gas Safety / Combustion Fault | View Details |
| A04 |
Boiler shows A04 and will not start, sometimes after power interruption
|
Control Board / Configuration Fault | View Details |
| A05 |
Boiler displays A05 and stops, often after overheating or poor circulation
|
Overheat Lockout / Safety Thermostat Tripped | View Details |
| A06 |
Boiler shows A06, fan may run but ignition does not start
|
Air Pressure Switch / Fan Proving Fault | View Details |
| A07 |
Boiler displays A07, intermittent lockouts especially in windy conditions
|
Flame Detection / Ionisation Fault (Intermittent) | View Details |
| A08 |
Boiler shows A08 and stops, often after a few minutes of operation
|
Flue Gas Temperature Too High | View Details |
| A09 |
Boiler displays A09, no heating or hot water, fan may not start
|
Fan / Air Flow Fault | View Details |
| A10 |
Boiler shows A10, will not start, sometimes after wiring changes
|
External Control / Thermostat Fault | View Details |
| A11 |
Boiler displays A11, intermittent operation, sometimes linked to DHW demand
|
Flow Sensor / Turbine Fault (DHW) | View Details |
| A12 |
Boiler shows A12, no heating, pump may run briefly then stop
|
Flow Switch / Minimum Flow Fault (Heating Circuit) | View Details |
| A13 |
Boiler displays A13, often associated with low system pressure or recent draining
|
Low Water Pressure Lockout | View Details |
| A14 |
Boiler shows A14, pressure gauge high, safety valve may drip
|
High System Pressure / Overpressure | View Details |
| A15 |
Boiler displays A15, no heating, pump may run continuously
|
NTC Sensor Fault – Flow Temperature | View Details |
| A16 |
Boiler shows A16, DHW temperature unstable or no hot water
|
NTC Sensor Fault – DHW Temperature | View Details |
| A17 |
Boiler displays A17, burner stops, pump may continue to run
|
Return Temperature Sensor Fault | View Details |
| A18 |
Boiler shows A18, no operation, sometimes after power surge
|
Internal Communication Error (PCB to Display/Module) | View Details |
| A19 |
Boiler displays A19, burner output limited or locked out
|
Gas Valve Modulation / Calibration Fault | View Details |
| A20 |
Boiler shows A20, no heating, pump may run, burner off
|
Pump Fault / No Circulation | View Details |
| A21 |
Boiler displays A21, frequent short cycling, poor temperature control
|
Outdoor Sensor / Weather Compensation Fault | View Details |
| A22 |
Boiler shows A22, DHW priority not working correctly, heating locked out
|
3-Way Diverter Valve Position Fault | View Details |
| A23 |
Boiler displays A23, no response to user interface, buttons not working
|
User Interface / Display Board Fault | View Details |
| A24 |
Boiler shows A24, burner stops, error often appears at high output
|
Primary Heat Exchanger Overheat / Flow Restriction | View Details |
| A25 |
Boiler displays A25, burner output limited, sometimes with noisy combustion
|
Condensate System / Siphon Fault | View Details |
| – |
Boiler condensate pipe dripping heavily or gurgling noises from condensate trap
|
Condensate Drainage Issue | View Details |
| – |
Boiler cycles on and off rapidly, room temperature unstable
|
Short Cycling / Control Misconfiguration | View Details |
| – |
Boiler display works but no response to heating or hot water demand
|
Control Input / Safety Chain Open | View Details |
| – |
Boiler does not start at all, no display or lights
|
No Power / Electrical Supply Fault | View Details |
| – |
Boiler emits smell of gas or combustion fumes
|
Gas Leak / Flue Gas Leakage | View Details |
| – |
Boiler fan runs continuously even when there is no heat demand
|
Fan Overrun / Control Fault | View Details |
| – |
Boiler frequently loses pressure and needs topping up
|
Chronic Pressure Loss | View Details |
| – |
Boiler ignites with a loud bang or popping noise
|
Delayed Ignition / Poor Combustion Setup | View Details |
| – |
Boiler leaking water from underneath the casing
|
Internal Water Leak | View Details |
| – |
Boiler makes loud banging or kettling noises during operation
|
Kettling / Localised Boiling in Heat Exchanger | View Details |
| – |
Boiler produces hot water but no central heating
|
Heating Circuit Demand / Diverter Fault | View Details |
| – |
Boiler room or casing excessively hot to touch during operation
|
Overheating / Poor Ventilation or Insulation Fault | View Details |
| – |
Boiler runs but produces no domestic hot water (combi or system with cylinder)
|
No Domestic Hot Water Production | View Details |
| – |
Radiators not heating properly while boiler appears to run normally
|
Poor Heat Distribution / Circulation Fault | View Details |
No matching codes found
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