BoilerFaultCodes Green LED
Your boiler is working exactly as it should and the green light simply confirms that the pilot light has successfully lit the main burner.
Potterton Housewarmer Fault codes & diagnostics
12 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Regular Natural Gas 8.8 kW 1994-2003 Discontinued
GC Numbers 41-591-1041-591-1341-591-1441-591-1541-591-16
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. 4 Emergency
7 High
1 Low
Just want the most common Potterton Housewarmer faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 12 documented codes
Tap any card for details
Lockout (Red LED) Your boiler has stopped trying to light itself because the small starter flame failed to ignite within the safety time limit.
Your boiler has stopped trying to light itself because the small starter flame failed to ignite within the safety time limit.
What to check first
- Locate the reset button or turn the control knob to the 'Reset' position.
- Hold for 5 seconds and release.
- If the fault persists after three attempts, contact a Gas Safe engineer to clear air from the gas line.
Parts commonly replaced
- Ignition Electrode
- Thermocouple
- Gas Valve
LOCKOUT a. Your boiler has stopped working because the small flame that lights the main burner is blocked or not staying lit.
Your boiler has stopped working because the small flame that lights the main burner is blocked or not staying lit.
Parts commonly replaced
- Pilot assembly
- Thermocouple
LOCKOUT b. Your boiler has detected that it is getting too hot and has automatically switched itself off as a safety precaution to prevent damage.
Your boiler has detected that it is getting too hot and has automatically switched itself off as a safety precaution to prevent damage.
Parts commonly replaced
- Overheat thermostat
- Pump
- PCB
LOCKOUT c. Your boiler has stopped working because it is not getting enough fresh air to burn its fuel safely, which could cause a dangerous buildup of fumes.
Your boiler has stopped working because it is not getting enough fresh air to burn its fuel safely, which could cause a dangerous buildup of fumes.
Parts commonly replaced
- Flue terminal
- Ventilation airways
- Air pressure switch
LOCKOUT d. Your boiler has detected that gases are not being safely cleared away through the flue, so it has shut down to prevent the build-up of dangerous fumes.
Your boiler has detected that gases are not being safely cleared away through the flue, so it has shut down to prevent the build-up of dangerous fumes.
Parts commonly replaced
- Flue fan
- Air pressure switch
- Flue seals
- Venturi
LOCKOUT: a Your boiler's small starter flame has become blocked by dust or debris, preventing the main heating system from firing up.
Your boiler's small starter flame has become blocked by dust or debris, preventing the main heating system from firing up.
Parts commonly replaced
- Pilot injector
- Thermocouple
Related codes
LOCKOUT: b Your boiler has switched itself off because it has gotten too hot, likely due to a blockage or a pump issue stopping the water from circulating.
Your boiler has switched itself off because it has gotten too hot, likely due to a blockage or a pump issue stopping the water from circulating.
What to check first
- Check that your radiator valves are fully open to allow water flow
- Ensure there is enough water pressure in the system (check the gauge)
- Press the reset button once the boiler has cooled down
Parts commonly replaced
- Circulating Pump
- Overheat Thermostat
- Thermistor
Related codes
LOCKOUT: c Your heater has shut down because it cannot pull in enough fresh air to operate safely, which increases the risk of dangerous carbon monoxide buildup.
Your heater has shut down because it cannot pull in enough fresh air to operate safely, which increases the risk of dangerous carbon monoxide buildup.
What to check first
- Check all external air vents or bricks for obstructions like leaves, debris, or bird nests
- Ensure vents are not covered by furniture, curtains, or new building work
- Clean the external air grille to remove dust or lint buildup
- Perform a reset as per manufacturer instructions once ventilation is verified as clear
Parts commonly replaced
- Air vent grille
- Ventilation ducting
Related codes
LOCKOUT: d Your boiler has shut down because the exhaust fumes are not being cleared away safely through the chimney or flue.
Your boiler has shut down because the exhaust fumes are not being cleared away safely through the chimney or flue.
Parts commonly replaced
- Flue fan
- Air pressure switch
- Flue ducting
Overheat (Red LED) Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage.
Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage.
Parts commonly replaced
- Overheat thermostat
- Pump
- PCB
Red LED (Overheat) Your boiler has switched itself off because it has gotten too hot, likely due to a circulation problem or a temporary blockage.
Your boiler has switched itself off because it has gotten too hot, likely due to a circulation problem or a temporary blockage.
What to check first
- Ensure all radiator valves are fully open and there is no air in the system.
- Allow the boiler to cool down completely for at least 20 minutes.
- Locate the manual reset button (usually behind the front flap or underneath) and press it firmly to clear the red light.
Parts commonly replaced
- Overheat Thermostat
- Circulation Pump
- Thermistor