BoilerFaultCodes Burner On (Green Light)
Your boiler is working normally and is currently firing to heat your radiators or hot water.
Potterton Promax FSB 30HE Fault codes & diagnostics
16 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
System Natural Gas 30 kW 2006-2008 Discontinued
GC Number 41-591-93
Replaced by: Promax System HE Plus
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. 13 High
3 Low
Just want the most common Potterton Promax FSB 30HE faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 16 documented codes
Tap any card for details
Condensate Pump (Green Light) Your boiler is currently pumping away waste water, which is a normal part of its operation and doesn't necessarily mean there is a fault.
Your boiler is currently pumping away waste water, which is a normal part of its operation and doesn't necessarily mean there is a fault.
What to check first
- Observe the light for a few minutes; it should turn off once the water has been drained.
- If the light stays on indefinitely, check the external white plastic pipe for blockages or ice.
- Ensure the pump's discharge hose isn't kinked or restricted.
Parts commonly replaced
- Condensate Pump
- External Condensate Pipework
FAN LOCKOUT Your boiler's fan, which safely clears exhaust gases from the unit, has stopped spinning correctly and prevented the system from firing up.
Your boiler's fan, which safely clears exhaust gases from the unit, has stopped spinning correctly and prevented the system from firing up.
Parts commonly replaced
- Fan Assembly
- Main PCB
- Wiring Harness
Flame Failure (Red Light) Your boiler has tried to light but failed to stay on, meaning the system has shut down for safety until it is reset or repaired.
Your boiler has tried to light but failed to stay on, meaning the system has shut down for safety until it is reset or repaired.
What to check first
- Check that your gas supply is active (check other gas appliances like a hob)
- Press the Reset button on the front of the boiler for a few seconds
- Ensure your condensate pipe has not frozen if it is currently very cold outside
Parts commonly replaced
- Ignition Electrode
- Flame Sensing Probe
- Gas Valve
- PCB
Flow Switch Your boiler has detected that there is not enough water flowing through it, so it has safely shut itself down to prevent damage to its internal components.
Your boiler has detected that there is not enough water flowing through it, so it has safely shut itself down to prevent damage to its internal components.
Parts commonly replaced
- Flow Switch
- Diverter Valve
- Central Heating Pump
Ignition Lockout Your boiler has failed to start after several attempts because it cannot safely light its internal flame.
Your boiler has failed to start after several attempts because it cannot safely light its internal flame.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Printed Circuit Board (PCB)
Mains On (Green Light)
Your boiler is receiving electrical power and is ready to operate as normal.
On * * Off Your boiler has stopped working because the internal fan, which clears exhaust gases, is failing to start or run correctly.
Your boiler has stopped working because the internal fan, which clears exhaust gases, is failing to start or run correctly.
Parts commonly replaced
- Flue fan assembly
- Fan wiring harness
- Printed Circuit Board (PCB)
On * On Off Your boiler has stopped working because a sensor that measures the water temperature is providing incorrect information, causing the system to shut down for safety.
Your boiler has stopped working because a sensor that measures the water temperature is providing incorrect information, causing the system to shut down for safety.
Parts commonly replaced
- NTC Thermistor
- Wiring harness
On Off * * Your boiler has stopped working because the pipe that drains away waste water is blocked, causing the system to temporarily shut down to prevent internal damage.
Your boiler has stopped working because the pipe that drains away waste water is blocked, causing the system to temporarily shut down to prevent internal damage.
What to check first
- Locate the plastic condensate pipe exiting your boiler or property near the exterior wall.
- Check the end of the pipe outside for blockages like ice, leaves, or debris.
- If the pipe is frozen, pour warm (not boiling) water over the frozen section to thaw it out.
- Reset your boiler using the reset button on the control panel.
Parts commonly replaced
- Condensate pump
- Condensate trap
- Float switch
On Off * Off Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage.
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage.
Parts commonly replaced
- Pump
- Diverter Valve
- NTC Sensor
- Heat Exchanger
On Off On Off Your boiler has shut down because water intended for your drain is backing up and has triggered a safety sensor.
Your boiler has shut down because water intended for your drain is backing up and has triggered a safety sensor.
What to check first
- Check if the condensate pump is plugged in and turned on at the wall.
- Inspect the thin plastic pipe leading from the pump for any kinks or blockages.
- If the weather is freezing, check if the external waste pipe is frozen and thaw it with warm (not boiling) water.
Parts commonly replaced
- Condensate Pump
- Condensate Discharge Pipework
On Off On Off * * On On Your boiler has shut down because it is unable to drain away the waste water it produces, causing a small internal reservoir to overflow.
Your boiler has shut down because it is unable to drain away the waste water it produces, causing a small internal reservoir to overflow.
What to check first
- Locate the external white plastic drainage pipe and check if it has frozen or is blocked with debris.
- If frozen, gently pour warm (not boiling) water over the pipe to melt the ice block.
- Check that the condensate pump (if fitted) is plugged in and switched on.
Parts commonly replaced
- Condensate pump
- Condensate trap
- External discharge pipework
On On On On Your boiler has detected that water is failing to drain away properly and has shut itself down to prevent internal flooding.
Your boiler has detected that water is failing to drain away properly and has shut itself down to prevent internal flooding.
Parts commonly replaced
- Condensate pump
- Condensate trap
- Float switch assembly
OVERHEAT LOCKOUT Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage to its internal components.
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage to its internal components.
Parts commonly replaced
- Flow pipe thermostat
- NTC thermistor
- PCB
THERMISTOR Your boiler's internal temperature sensor has stopped sending a reliable signal, which means the system cannot safely monitor how hot the water is getting.
Your boiler's internal temperature sensor has stopped sending a reliable signal, which means the system cannot safely monitor how hot the water is getting.
Parts commonly replaced
- NTC Thermistor
- Wiring Harness
- Main PCB