BoilerFaultCodes 00
Your boiler is operating normally and there are no faults currently detected by the system.
Saunier Duval Isomax F30E Fault codes & diagnostics
15 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 30 kW 2002-2007 Discontinued
Replaced by: Isomax Condens
Download the Saunier Duval Isomax F30E 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. 13 High
1 Medium
1 Low
Just want the most common Saunier Duval Isomax F30E faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 15 documented codes
Tap any card for details
02 Your boiler has stopped working because it cannot properly clear away exhaust fumes or draw in fresh air to burn gas safely.
Your boiler has stopped working because it cannot properly clear away exhaust fumes or draw in fresh air to burn gas safely.
Parts commonly replaced
- Fan
- Air pressure switch
- Venturi tube
- Flue seals
Related codes
04 Your boiler is failing to light the gas or cannot tell that the flame has successfully ignited, meaning it won't be able to provide heating or hot water.
Your boiler is failing to light the gas or cannot tell that the flame has successfully ignited, meaning it won't be able to provide heating or hot water.
What to check first
- Check if your home gas supply is active by testing another gas appliance like a hob.
- Inspect the condensate pipe (plastic pipe leadings outdoors) to ensure it isn't frozen or blocked.
- Try to reset the boiler by turning the main dial to the reset position for five seconds and then back to the heater symbol.
Parts commonly replaced
- Ignition electrodes
- Gas valve
- Printed Circuit Board (PCB)
06 Your boiler's internal temperature sensor has stopped sending the correct signal, meaning the system doesn't know how hot the water is and has shut down for safety.
Your boiler's internal temperature sensor has stopped sending the correct signal, meaning the system doesn't know how hot the water is and has shut down for safety.
Parts commonly replaced
- Central Heating (CH) thermistor
- NTC sensor wiring harness
Related codes
07 Your boiler is struggling to accurately measure the temperature of your hot water, which usually means it cannot provide consistent or safe water temperatures.
Your boiler is struggling to accurately measure the temperature of your hot water, which usually means it cannot provide consistent or safe water temperatures.
Parts commonly replaced
- DHW Thermistor (NTC Sensor)
- Wiring harness / Connector
Related codes
08 Your boiler's hot water storage tank sensor is failing to report the correct temperature, which might lead to inconsistent or no hot water.
Your boiler's hot water storage tank sensor is failing to report the correct temperature, which might lead to inconsistent or no hot water.
Parts commonly replaced
- Storage vessel thermistor (NTC sensor)
- Wiring harness
Related codes
09 Your boiler has lost track of the water pressure inside the system because the internal sensor is failing or sending an incorrect signal.
Your boiler has lost track of the water pressure inside the system because the internal sensor is failing or sending an incorrect signal.
Parts commonly replaced
- Water pressure sensor
- Sensor wiring harness
- Main PCB
Related codes
10 Your boiler has stopped working because the fan that helps remove waste gases is not spinning correctly.
Your boiler has stopped working because the fan that helps remove waste gases is not spinning correctly.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
- Air pressure switch
11 Your boiler is struggling to circulate water because the internal pump responsible for moving heat around your home is stuck.
Your boiler is struggling to circulate water because the internal pump responsible for moving heat around your home is stuck.
Parts commonly replaced
- Central heating pump
- Pump capacitor
Related codes
12 Your boiler's control panel has lost communication with the internal computer, meaning it cannot receive your instructions on how to heat your home.
Your boiler's control panel has lost communication with the internal computer, meaning it cannot receive your instructions on how to heat your home.
Parts commonly replaced
- Digital User Interface board
- Main Printed Circuit Board (PCB)
- Wiring Harness
Related codes
13 Your boiler's internal computer has developed a fault and can no longer control the heating system correctly.
Your boiler's internal computer has developed a fault and can no longer control the heating system correctly.
Parts commonly replaced
- Main PCB (Printed Circuit Board)
- Wiring harness connectors
14 Your boiler has shut down because a temperature sensor has detected that the water inside is getting too hot, likely due to a circulation problem.
Your boiler has shut down because a temperature sensor has detected that the water inside is getting too hot, likely due to a circulation problem.
What to check first
- Check that all radiator valves are fully open to allow water to flow.
- Check that the boiler pressure is between 1.0 and 1.5 bar on the gauge.
- Reset the boiler using the power switch to see if the fault clears.
Parts commonly replaced
- Circulation Pump
- Overheat Thermostat (High Limit Stat)
- Flow Temperature Sensor (NTC)
Related codes
15 Your boiler has detected a problem with how it controls the gas supply, preventng it from lighting safely.
Your boiler has detected a problem with how it controls the gas supply, preventng it from lighting safely.
Parts commonly replaced
- Gas Valve
- Stepper Motor
- Control Board
20 Your boiler's internal computer parts are failing to talk to each other, meaning the system cannot receive the instructions it needs to work.
Your boiler's internal computer parts are failing to talk to each other, meaning the system cannot receive the instructions it needs to work.
Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Interface Display Board
- Wiring Harness
Pictogram of a spark Your boiler is failing to light the flame, which is likely due to a lack of gas reaching the unit or a problem with the ignition system.
Your boiler is failing to light the flame, which is likely due to a lack of gas reaching the unit or a problem with the ignition system.
What to check first
- Check if other gas appliances, such as a hob, are working to confirm your gas supply is active.
- Verify that your gas meter has credit if you use a pre-payment meter.
- Check that the gas isolation valve under the boiler is in the 'on' or 'open' position (usually parallel to the pipe).
- Press the reset button on the boiler control panel.
Parts commonly replaced
- Gas Valve
- Ignition Electrode
- Spark Generator
- Printed Circuit Board (PCB)