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
PDF
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 5 High
2 Low
4 Unrated
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
Appliance frost protection intervenes (heating heat exchanger)
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
Sensor fault S1
20, 21, 22, 23, 24
Sensor fault S2
29, 30
Gas valve relay fault