Hoval
Hoval 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 with A01 on display, burner does not ignite, red fault LED lit
Ignition Failure / No Flame Detection
A02
Boiler attempts to start, fan runs briefly, then locks out with A02, no flame established
Gas Valve or Gas Train Fault
A03
Boiler locks out with A03, burner shuts down shortly after ignition or during operation
Flame Loss During Operation
A04
Boiler displays A04 and will not start, fan does not run
Fan / Air Pressure Fault
A05
Boiler shows A05, attempts to start but shuts down quickly, sometimes with loud ignition noise
Incorrect Combustion / Ignition Control Fault
A06
Boiler locks out with A06, display may indicate flue or air pressure error
Flue Gas / Air Pressure Switch Fault
A07
Boiler shows A07, burner stops and cannot restart until reset
Overheat / Safety Thermostat Trip
A08
Boiler displays A08, no heating or hot water, fan may run but burner does not ignite.
Safety Chain Interruption (Limit or Flow Switch Open)
A09
Boiler shows A09, intermittent lockouts, sometimes after long operation.
Flue Gas Temperature Too High
A10
Boiler displays A10, no burner operation, may indicate low water pressure or flow.
Low Water Pressure / Water Shortage
A11
Boiler shows A11, burner stops, display may indicate return temperature too high.
Return Temperature Too High / Flow Restriction
A12
Boiler displays A12, no hot water in DHW mode; heating may still work.
DHW Flow Detection Fault
A13
Boiler shows A13, burner output limited or locked out, often in condensing operation.
Condensate Drain / Siphon Fault
A14
Boiler displays A14, no burner operation, may indicate a sensor fault.
Flow Temperature Sensor Fault
A15
Boiler shows A15, burner stops, may indicate a return sensor fault.
Return Temperature Sensor Fault
A16
Boiler displays A16, burner output limited, may show an outside temperature error on weather-compensated systems.
Outdoor Temperature Sensor Fault
A17
Boiler shows A17, burner does not start, may indicate a flue gas sensor or safety device fault.
Flue Gas Safety Device Trip / Sensor Fault
A18
Boiler displays A18, control panel unresponsive or intermittent, sometimes after power fluctuations.
Control PCB / Communication Fault
A19
Boiler shows A19, burner output limited, which may indicate a sensor calibration or parameter error.
Configuration / Parameter Fault
E01
Boiler shows E01 (warning), continues to operate at reduced output.
Flow Temperature Sensor Warning / Drift
E02
Boiler shows E02 (warning), outside temperature reading unrealistic.
Outdoor Sensor Warning / Out-of-Range Reading
E03
Boiler shows E03, pump symbol flashing, heating performance reduced.
Pump Speed / Pump Control Warning
E04
Boiler shows E04, DHW temperature fluctuates (warning only).
DHW Temperature Control Instability
E05
Boiler shows E05, communication symbol flashing between the boiler and Hoval TopTronic or room controller.
Communication Bus Fault
Symptom
Boiler display is on but unresponsive to button presses; heating and DHW continue in last mode.
Control Panel/Keypad Failure
Symptom
Boiler frequently loses pressure and needs topping up every few days.
Chronic Pressure Loss
Symptom
Boiler leaking water from underneath the casing or from pipe connections.
Internal Water Leak
Symptom
Boiler makes loud banging or knocking noises (kettling) during operation.
Boiler Kettling / Localised Boiling
Symptom
Boiler starts then shuts down after a few seconds, repeatedly, without showing an error code.
Unstable Flame/Early Shutdown
Symptom
Radiators are only warm at the top, or some radiators remain cold while the boiler is running.
Poor Heat Distribution / Sludge Blockage
Symptom
The boiler cycles on and off frequently with short run times, and rooms do not reach the set temperature comfortably.
Short Cycling / Control Mismatch
Symptom
The boiler does not start at all; there is no display or lights.
No Power / Electrical Supply Fault
Symptom
The boiler emits a smell of gas around the casing or flue area.
Gas Leak / Incomplete Combustion
Symptom
The boiler emits a strong burning or plastic smell during operation.
Overheating Electrical Component or Insulation
Symptom
The boiler fan runs, but the burner does not ignite, and no error code is displayed.
Intermittent Ignition / Control Logic Issue
Symptom
The boiler is very noisy, with vibration transmitted to pipework and the building structure.
Mechanical Vibration / Mounting Fault
Symptom
The boiler provides hot water, but the temperature fluctuates between hot and cold during a shower.
Inconsistent DHW Temperature
Symptom
The boiler runs but provides no domestic hot water, while heating works normally.
DHW Priority / Diverter Fault
Symptom
The boiler runs, but the room temperature overshoots the setpoint and becomes too hot.
Overheating Rooms / Control Overshoot
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A01 |
Boiler locks out with A01 on display, burner does not ignite, red fault LED lit
|
Ignition Failure / No Flame Detection | View Details |
| A02 |
Boiler attempts to start, fan runs briefly, then locks out with A02, no flame established
|
Gas Valve or Gas Train Fault | View Details |
| A03 |
Boiler locks out with A03, burner shuts down shortly after ignition or during operation
|
Flame Loss During Operation | View Details |
| A04 |
Boiler displays A04 and will not start, fan does not run
|
Fan / Air Pressure Fault | View Details |
| A05 |
Boiler shows A05, attempts to start but shuts down quickly, sometimes with loud ignition noise
|
Incorrect Combustion / Ignition Control Fault | View Details |
| A06 |
Boiler locks out with A06, display may indicate flue or air pressure error
|
Flue Gas / Air Pressure Switch Fault | View Details |
| A07 |
Boiler shows A07, burner stops and cannot restart until reset
|
Overheat / Safety Thermostat Trip | View Details |
| A08 |
Boiler displays A08, no heating or hot water, fan may run but burner does not ignite.
|
Safety Chain Interruption (Limit or Flow Switch Open) | View Details |
| A09 |
Boiler shows A09, intermittent lockouts, sometimes after long operation.
|
Flue Gas Temperature Too High | View Details |
| A10 |
Boiler displays A10, no burner operation, may indicate low water pressure or flow.
|
Low Water Pressure / Water Shortage | View Details |
| A11 |
Boiler shows A11, burner stops, display may indicate return temperature too high.
|
Return Temperature Too High / Flow Restriction | View Details |
| A12 |
Boiler displays A12, no hot water in DHW mode; heating may still work.
|
DHW Flow Detection Fault | View Details |
| A13 |
Boiler shows A13, burner output limited or locked out, often in condensing operation.
|
Condensate Drain / Siphon Fault | View Details |
| A14 |
Boiler displays A14, no burner operation, may indicate a sensor fault.
|
Flow Temperature Sensor Fault | View Details |
| A15 |
Boiler shows A15, burner stops, may indicate a return sensor fault.
|
Return Temperature Sensor Fault | View Details |
| A16 |
Boiler displays A16, burner output limited, may show an outside temperature error on weather-compensated systems.
|
Outdoor Temperature Sensor Fault | View Details |
| A17 |
Boiler shows A17, burner does not start, may indicate a flue gas sensor or safety device fault.
|
Flue Gas Safety Device Trip / Sensor Fault | View Details |
| A18 |
Boiler displays A18, control panel unresponsive or intermittent, sometimes after power fluctuations.
|
Control PCB / Communication Fault | View Details |
| A19 |
Boiler shows A19, burner output limited, which may indicate a sensor calibration or parameter error.
|
Configuration / Parameter Fault | View Details |
| E01 |
Boiler shows E01 (warning), continues to operate at reduced output.
|
Flow Temperature Sensor Warning / Drift | View Details |
| E02 |
Boiler shows E02 (warning), outside temperature reading unrealistic.
|
Outdoor Sensor Warning / Out-of-Range Reading | View Details |
| E03 |
Boiler shows E03, pump symbol flashing, heating performance reduced.
|
Pump Speed / Pump Control Warning | View Details |
| E04 |
Boiler shows E04, DHW temperature fluctuates (warning only).
|
DHW Temperature Control Instability | View Details |
| E05 |
Boiler shows E05, communication symbol flashing between the boiler and Hoval TopTronic or room controller.
|
Communication Bus Fault | View Details |
| – |
Boiler display is on but unresponsive to button presses; heating and DHW continue in last mode.
|
Control Panel/Keypad Failure | View Details |
| – |
Boiler frequently loses pressure and needs topping up every few days.
|
Chronic Pressure Loss | View Details |
| – |
Boiler leaking water from underneath the casing or from pipe connections.
|
Internal Water Leak | View Details |
| – |
Boiler makes loud banging or knocking noises (kettling) during operation.
|
Boiler Kettling / Localised Boiling | View Details |
| – |
Boiler starts then shuts down after a few seconds, repeatedly, without showing an error code.
|
Unstable Flame/Early Shutdown | View Details |
| – |
Radiators are only warm at the top, or some radiators remain cold while the boiler is running.
|
Poor Heat Distribution / Sludge Blockage | View Details |
| – |
The boiler cycles on and off frequently with short run times, and rooms do not reach the set temperature comfortably.
|
Short Cycling / Control Mismatch | View Details |
| – |
The boiler does not start at all; there is no display or lights.
|
No Power / Electrical Supply Fault | View Details |
| – |
The boiler emits a smell of gas around the casing or flue area.
|
Gas Leak / Incomplete Combustion | View Details |
| – |
The boiler emits a strong burning or plastic smell during operation.
|
Overheating Electrical Component or Insulation | View Details |
| – |
The boiler fan runs, but the burner does not ignite, and no error code is displayed.
|
Intermittent Ignition / Control Logic Issue | View Details |
| – |
The boiler is very noisy, with vibration transmitted to pipework and the building structure.
|
Mechanical Vibration / Mounting Fault | View Details |
| – |
The boiler provides hot water, but the temperature fluctuates between hot and cold during a shower.
|
Inconsistent DHW Temperature | View Details |
| – |
The boiler runs but provides no domestic hot water, while heating works normally.
|
DHW Priority / Diverter Fault | View Details |
| – |
The boiler runs, but the room temperature overshoots the setpoint and becomes too hot.
|
Overheating Rooms / Control Overshoot | View Details |
No matching codes found
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