BoilerFaultCodes 0
Your boiler is currently running its pump to circulate leftover heat, which is a normal protective process and not an active fault.
Atmos Intersystem HE26 Fault codes & diagnostics
19 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
System Natural Gas 2004-2018 Discontinued
GC Number 41-249-05
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Severity at a glance
Each cell = one fault code. Hover to identify. 16 High
3 Low
Just want the most common Atmos Intersystem HE26 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 19 documented codes
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1
Your boiler has reached the temperature you set on the thermostat and is simply taking a break until it needs to heat up again.
2 Your boiler is currently running a routine internal check to ensure all its safety systems are working correctly before it starts up.
Your boiler is currently running a routine internal check to ensure all its safety systems are working correctly before it starts up.
What to check first
- Wait for 5 to 10 minutes to allow the self-test process to complete automatically
- If the code persists, try turning the boiler off at the fused spur for 30 seconds
- Turn the power back on and allow the unit to reboot
Related codes
4 Your boiler is failing to light the flame needed to provide you with heating and hot water.
Your boiler is failing to light the flame needed to provide you with heating and hot water.
Parts commonly replaced
- Ignition electrode
- Ignition lead
- Gas valve
Related codes
5 Your boiler is struggling to detect that the central heating system is active, which is likely preventing your radiators from warming up.
Your boiler is struggling to detect that the central heating system is active, which is likely preventing your radiators from warming up.
Parts commonly replaced
- Flow switch
- DHW sensor
- Control board
Related codes
6 Your boiler is struggling to light or detect a steady flame, which is preventing your heating and hot water from working.
Your boiler is struggling to light or detect a steady flame, which is preventing your heating and hot water from working.
Parts commonly replaced
- Ignition cable
- Spark electrode/probe
- Ignition unit
- Control board
Related codes
8 Your boiler has stopped working because the internal fan, which safely exhausts fumes, is not spinning at the correct speed.
Your boiler has stopped working because the internal fan, which safely exhausts fumes, is not spinning at the correct speed.
Parts commonly replaced
- Fan assembly
- Wiring harness
- Main PCB (Controller)
Related codes
10 Your boiler's internal temperature sensor has stopped sending information, causing the system to shut down for safety.
Your boiler's internal temperature sensor has stopped sending information, causing the system to shut down for safety.
Parts commonly replaced
- S1 Flow Temperature Sensor
- Wiring harness
Related codes
11 Your boiler has stopped working because one of its internal temperature sensors is unable to send a correct reading to the main control board.
Your boiler has stopped working because one of its internal temperature sensors is unable to send a correct reading to the main control board.
Parts commonly replaced
- Flow Temperature Sensor (S1)
- Sensor Wiring Harness
Related codes
12 Your boiler has stopped working because one of its internal heat sensors is reporting a fault or has a damaged connection.
Your boiler has stopped working because one of its internal heat sensors is reporting a fault or has a damaged connection.
Parts commonly replaced
- Flow Temperature Sensor (S1)
- Sensor Wiring Harness
Related codes
13 Your boiler has stopped working because its main temperature sensor is unable to provide a reading to the control board.
Your boiler has stopped working because its main temperature sensor is unable to provide a reading to the control board.
Parts commonly replaced
- S1 Temperature Sensor (NTC)
- Wiring harness
Related codes
14 Your boiler has stopped working because one of its internal temperature sensors is providing an incorrect reading or is no longer communicating with the control board.
Your boiler has stopped working because one of its internal temperature sensors is providing an incorrect reading or is no longer communicating with the control board.
Parts commonly replaced
- S1 Flow Temperature Sensor
- Wiring harness
Related codes
20 Your boiler has stopped heating because one of its internal temperature sensors is not reporting correctly and likely needs professional attention.
Your boiler has stopped heating because one of its internal temperature sensors is not reporting correctly and likely needs professional attention.
Parts commonly replaced
- S2 Flow/Return Temperature Sensor
- Sensor wiring harness
Related codes
21 Your boiler has stopped working because a built-in temperature sensor has developed a fault or is sending an incorrect signal.
Your boiler has stopped working because a built-in temperature sensor has developed a fault or is sending an incorrect signal.
Parts commonly replaced
- Temperature Sensor (S2)
- Sensor Wiring Harness
Related codes
22 Your boiler has stopped working because one of its internal temperature sensors is providing an incorrect reading or has lost its connection.
Your boiler has stopped working because one of its internal temperature sensors is providing an incorrect reading or has lost its connection.
Parts commonly replaced
- NTC Temperature Sensor (S2)
- Sensor wiring harness
Related codes
23 Your boiler has stopped working because one of its internal temperature sensors is providing an incorrect reading or has developed a connection fault.
Your boiler has stopped working because one of its internal temperature sensors is providing an incorrect reading or has developed a connection fault.
Parts commonly replaced
- S2 Temperature Sensor (NTC)
- Wiring Harness
Related codes
24 Your boiler has stopped working because its internal temperature sensor is reporting a technical error or has lost its connection.
Your boiler has stopped working because its internal temperature sensor is reporting a technical error or has lost its connection.
Parts commonly replaced
- S2 Return Temperature Sensor
- Sensor wiring harness
Related codes
29 Your boiler's internal computer brain has developed a fault with the electrical switch that controls the gas flow, meaning the system cannot safely start up.
Your boiler's internal computer brain has developed a fault with the electrical switch that controls the gas flow, meaning the system cannot safely start up.
Parts commonly replaced
- Main PCB (Control Board)
- Gas Valve
Related codes
30 Your boiler's internal computer has suffered a critical electrical failure and can no longer safely operate the gas supply.
Your boiler's internal computer has suffered a critical electrical failure and can no longer safely operate the gas supply.
Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Control Box