BoilerFaultCodes 0
Your boiler is currently running its pump to safely circulate leftover heat, which is a normal part of the cooling process rather than a fault.
Atmos Intersystem HE40 C Fault codes & diagnostics
11 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
System Natural Gas 2004-2018 Discontinued
GC Number 41-249-07
Download the Atmos Intersystem HE40 C manual
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Severity at a glance
Each cell = one fault code. Hover to identify. 1 Emergency
7 High
3 Low
Just want the most common Atmos Intersystem HE40 C faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 11 documented codes
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1 Your boiler has successfully reached its target temperature and is now resting as it should.
Your boiler has successfully reached its target temperature and is now resting as it should.
What to check first
- No action required
- The boiler is operating normally
2 Your boiler is currently performing an internal safety check, which is a normal part of its startup process, but it has not progressed past this stage.
Your boiler is currently performing an internal safety check, which is a normal part of its startup process, but it has not progressed past this stage.
Parts commonly replaced
- Control Board
- Wiring Harness
Related codes
4 Your boiler is failing to light the internal flame needed to provide heating or hot water.
Your boiler is failing to light the internal flame needed to provide heating or hot water.
Parts commonly replaced
- Ignition electrode
- Ignition lead
- Gas valve
Related codes
5 Your boiler has detected a problem with the internal sensor that monitors the heating circuit, meaning it cannot reliably provide central heating.
Your boiler has detected a problem with the internal sensor that monitors the heating circuit, meaning it cannot reliably provide central heating.
Parts commonly replaced
- Flow Temperature Sensor
- Return Temperature Sensor
- Wiring Harness
Related codes
6 Your boiler is failing to detect a flame, meaning it cannot stay lit to provide heating or hot water.
Your boiler is failing to detect a flame, meaning it cannot stay lit to provide heating or hot water.
Parts commonly replaced
- Ignition cable
- Spark probe
- Ignition unit
- Controller
Related codes
7 Your boiler has detected that the temperature inside the unit is dropping close to freezing and has temporarily activated its built-in frost protection to stop the water inside from turning to ice.
Your boiler has detected that the temperature inside the unit is dropping close to freezing and has temporarily activated its built-in frost protection to stop the water inside from turning to ice.
What to check first
- Check that your heating is not accidentally switched off completely.
- Ensure your property's room thermostat is set high enough to call for heat.
- Verify that the boiler's external condensate pipe is not blocked or frozen outside.
Parts commonly replaced
- NTC Temperature Sensor
- PCB
Related codes
8 Your boiler has stopped working because the internal fan is moving at the wrong speed or cannot communicate with the main control board.
Your boiler has stopped working because the internal fan is moving at the wrong speed or cannot communicate with the main control board.
Parts commonly replaced
- Fan assembly
- Control PCB
- Wiring harness
Related codes
10, 11, 12, 13, 14 Your boiler is temporarily locked out because one of its internal temperature monitors is sending an incorrect reading.
Your boiler is temporarily locked out because one of its internal temperature monitors is sending an incorrect reading.
Parts commonly replaced
- NTC Thermistor
- Temperature Sensor
- Wiring Harness
Related codes
20, 21, 22, 23, 24 Your boiler has temporarily stopped working because it is getting incorrect temperature readings from one of its internal sensors.
Your boiler has temporarily stopped working because it is getting incorrect temperature readings from one of its internal sensors.
Parts commonly replaced
- Temperature Sensor
- Wiring Harness
Related codes
29, 30 Your boiler has detected an internal electrical problem with the safety component that controls the gas supply, meaning it has safely shut down to prevent any risk.
Your boiler has detected an internal electrical problem with the safety component that controls the gas supply, meaning it has safely shut down to prevent any risk.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Gas Valve