Common questions about Ideal codes · Search all brands by code or symptom
What is safe for you to do
Every code here follows the same safety rules. You can:
- press the reset button once, as your user guide shows;
- for low-pressure codes, top up the pressure with the filling loop, as your user guide shows;
- for ignition and flame-loss codes, check the gas is on at the meter and a prepayment meter has credit;
- thaw a frozen plastic condensate pipe outside with warm (not boiling) water;
- check the thermostat, timer and power to the boiler.
Never open the boiler casing. Only a Gas Safe registered engineer may work inside a gas boiler. Codes marked Engineer after one reset have no homeowner fix: reset once, then leave them to an engineer. Codes marked Safe checks first list the one check that relates to that code.
Ideal Logic Max Combi C (C24 / C30 / C35, IE edition manual)
Logic Max Combi C boilers that show codes use F (fault) and L (lockout) codes, e.g. L2. Newer Logic Max Combi 2 models show the fault in words instead (e.g. 'Ignition Lockout').
Source: Ideal Logic Max Combi C Installation & Servicing (C24IE, C30IE, C35IE), doc. UIN 223440 A05, User's section 8, Fault codes (PDF p. 80). Open the manual (PDF) (Copy hosted by a UK trade site (no manufacturer-hosted copy found))
Ignition / flame
F2 Ideal Logic Max Combi C
Safe checks firstIgnition / flameWhat it means
Flame loss.
Likely causes
Gas off at the meter, no prepay credit, low gas pressure, a frozen condensate pipe, or a flue, electrode or gas valve fault.
What you can safely do
Check another gas appliance such as the hob works, the gas meter valve is on and, on a prepayment meter, there is credit. In freezing weather, check the plastic condensate pipe outside: if it is frozen, pour warm (not boiling) water along it. Then press reset once. If the code comes back, stop resetting.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the gas supply is fine and the code returns after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does F2 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F2 is listed in the manufacturer's table as "Flame loss". Check another gas appliance works, the meter valve is on and any prepay meter has credit, then reset once. If it returns, book a Gas Safe registered engineer.
L2 Ideal Logic Max Combi C
Safe checks firstIgnition / flameWhat it means
Ignition lockout: the boiler failed to light.
Likely causes
A frozen or blocked condensate pipe, gas off at the meter, no prepay credit, or an ignition, flue or gas valve fault.
What you can safely do
Check another gas appliance such as the hob works, the gas meter valve is on and, on a prepayment meter, there is credit. In freezing weather, check the plastic condensate pipe outside: if it is frozen, pour warm (not boiling) water along it. Then press reset once. If the code comes back, stop resetting.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the gas supply is fine and the code returns after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does L2 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, L2 is listed in the manufacturer's table as "Ignition lockout: the boiler failed to light". Check another gas appliance works, the meter valve is on and any prepay meter has credit, then reset once. If it returns, book a Gas Safe registered engineer.
L6 Ideal Logic Max Combi C
Engineer after one resetIgnition / flameWhat it means
False flame lockout.
Likely causes
Flame detection electrode, wiring or gas valve.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does L6 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, L6 is listed in the manufacturer's table as "False flame lockout". Likely causes include flame detection electrode, wiring or gas valve. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Water pressure / circulation
F1 Ideal Logic Max Combi C
Safe checks firstWater pressure / circulationWhat it means
Low water pressure.
Likely causes
Water lost from the heating system (leak, pressure relief valve, bleeding radiators) or a flat expansion vessel.
What you can safely do
Look at the pressure gauge while the boiler is cold. If it is below about 1 bar, top it up with the filling loop exactly as your user guide shows, to about 1–1.5 bar or the figure in your guide, then close the loop fully. Check the radiator valves are open, then press reset once.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if you have to top up more than once every few months, the gauge goes above about 2.5 bar when hot, water drips from the outside overflow pipe, or the code returns after topping up.
What does F1 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F1 is listed in the manufacturer's table as "Low water pressure". With the boiler cold, check the pressure gauge; if it is below the level in your user guide, top it up as the guide shows, then reset once. If it returns, book a Gas Safe registered engineer.
FU Ideal Logic Max Combi C
Engineer after one resetWater pressure / circulationWhat it means
Flow/return temperature difference greater than 50 °C.
Likely causes
Poor circulation through the boiler: pump, air, a blocked filter or closed valves.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if you have to top up more than once every few months, the gauge goes above about 2.5 bar when hot, water drips from the outside overflow pipe, or the code returns after topping up.
What does FU mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, FU is listed in the manufacturer's table as "Flow/return temperature difference greater than 50 °C". Reset once; if the code comes back, book a Gas Safe registered engineer and quote the full code. Do not open the casing.
Temperature / overheat
L1 Ideal Logic Max Combi C
Engineer after one resetTemperature / overheatWhat it means
Flow temperature overheat or no water flow.
Likely causes
Low pressure, air, a stuck pump, closed valves or a blocked system.
What you can safely do
Let the boiler cool for 20 to 30 minutes, then press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Overheat shut-downs are safety devices doing their job, so this is engineer-only.
What does L1 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, L1 is listed in the manufacturer's table as "Flow temperature overheat or no water flow". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Flue / fan / air
F3 Ideal Logic Max Combi C
Engineer after one resetFlue / fan / airWhat it means
Fan fault.
Likely causes
A failed fan, fan wiring or the control board.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the terminal looks clear and the code returns. Flue and fan faults can affect how combustion gases leave your home, so this is engineer-only.
What does F3 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F3 is listed in the manufacturer's table as "Fan fault". Likely causes include a failed fan, fan wiring or the control board. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Sensors / thermistors
F4 Ideal Logic Max Combi C
Engineer after one resetSensors / thermistorsWhat it means
Flow thermistor fault.
Likely causes
Failed flow thermistor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does F4 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F4 is listed in the manufacturer's table as "Flow thermistor fault". Likely causes include failed flow thermistor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
L4 Ideal Logic Max Combi C
Engineer after one resetSensors / thermistorsWhat it means
Flow thermistor fault (locking version).
Likely causes
Failed flow thermistor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does L4 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, L4 is listed in the manufacturer's table as "Flow thermistor fault (locking version)". Likely causes include failed flow thermistor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F5 Ideal Logic Max Combi C
Engineer after one resetSensors / thermistorsWhat it means
Return thermistor fault.
Likely causes
Failed return thermistor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does F5 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F5 is listed in the manufacturer's table as "Return thermistor fault". Likely causes include failed return thermistor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
L5 Ideal Logic Max Combi C
Engineer after one resetSensors / thermistorsWhat it means
Return thermistor fault (locking version).
Likely causes
Failed return thermistor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does L5 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, L5 is listed in the manufacturer's table as "Return thermistor fault (locking version)". Likely causes include failed return thermistor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F6 Ideal Logic Max Combi C
Engineer after one resetSensors / thermistorsWhat it means
Outside sensor failure.
Likely causes
Faulty or disconnected weather sensor.
What you can safely do
Nothing urgent: the boiler normally keeps heating without the outdoor sensor, using a fixed setting. Press reset once to see if it clears.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does F6 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F6 is listed in the manufacturer's table as "Outside sensor failure". Likely causes include faulty or disconnected weather sensor. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
FA Ideal Logic Max Combi C
Engineer after one resetSensors / thermistorsWhat it means
Negative flow/return thermistor differential: the return reads hotter than the flow.
Likely causes
Thermistor fault or sensors reading incorrectly.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does FA mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, FA is listed in the manufacturer's table as "Negative flow/return thermistor differential: the return reads hotter than the flow". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
PCB / electrical
F7 Ideal Logic Max Combi C
Safe checks firstPCB / electricalWhat it means
Low mains voltage.
Likely causes
Low supply voltage at the property.
What you can safely do
Check whether lights are dimming or other appliances are struggling. If they are, contact an electrician or your electricity network operator (call 105 for a power cut). Then press reset once.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if your mains supply is fine and the code continues, so the boiler's own supply and board can be checked.
What does F7 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F7 is listed in the manufacturer's table as "Low mains voltage". Likely causes include low supply voltage at the property. Reset once; if the code comes back, book a Gas Safe registered engineer and quote the full code. Do not open the casing.
F9 Ideal Logic Max Combi C
Engineer after one resetPCB / electricalWhat it means
Unconfigured or faulty PCB, or a gas valve short circuit.
Likely causes
A replacement board not set up, a board fault or a gas valve short.
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does F9 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, F9 is listed in the manufacturer's table as "Unconfigured or faulty PCB, or a gas valve short circuit". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
L9 Ideal Logic Max Combi C
Engineer after one resetPCB / electricalWhat it means
Unconfigured or faulty PCB, or a gas valve short circuit (locking version).
Likely causes
A replacement board not set up, a board fault or a gas valve short.
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does L9 mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, L9 is listed in the manufacturer's table as "Unconfigured or faulty PCB, or a gas valve short circuit (locking version)". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Other / controls
LC Ideal Logic Max Combi C
Safe checks firstOther / controlsWhat it means
Five boiler resets within 15 minutes.
Likely causes
Repeated resetting of an underlying fault.
What you can safely do
Stop resetting. Switch the boiler off at its mains switch, wait at least 15 minutes, then check the gas supply and pressure before trying one more reset.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer now. Repeated resets mean an underlying fault is still there; tell them which code you were resetting.
What does LC mean on an Ideal Logic Max Combi C boiler?
On an Ideal Logic Max Combi C, LC is listed in the manufacturer's table as "Five boiler resets within 15 minutes". Likely causes include repeated resetting of an underlying fault. Reset once; if the code comes back, book a Gas Safe registered engineer and quote the full code. Do not open the casing.
Ideal Logic Combi (24 / 30 / 35)
The Logic Combi alternates two characters on its display, e.g. 'F' then '1' for F1.
Source: Ideal Logic Combi 24, 30, 35 Installation and Servicing (with User's Guide), doc. UIN 204626 A12 (January 2014), User's Guide p. 7 (PDF p. 71), Fault codes table. Open the manual (PDF) (Manufacturer copy)
Ignition / flame
F2 Ideal Logic Combi
Safe checks firstIgnition / flameWhat it means
Flame loss.
Likely causes
Gas off at the meter, no credit on a prepayment meter, low gas pressure, a frozen condensate pipe, or an electrode, flue or gas valve fault.
What you can safely do
Check another gas appliance such as the hob works, the gas meter valve is on and, on a prepayment meter, there is credit. In freezing weather, check the plastic condensate pipe outside: if it is frozen, pour warm (not boiling) water along it. Then press reset once. If the code comes back, stop resetting.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the gas supply is fine and the code returns after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does F2 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F2 is listed in the manufacturer's table as "Flame loss". Check another gas appliance works, the meter valve is on and any prepay meter has credit, then reset once. If it returns, book a Gas Safe registered engineer.
L2 Ideal Logic Combi
Safe checks firstIgnition / flameWhat it means
Flame loss lockout (this manual lists L2 alongside F2 as flame loss).
Likely causes
Gas off at the meter, no prepay credit, a frozen or blocked condensate pipe, or an ignition, flue or gas valve fault.
What you can safely do
Check another gas appliance such as the hob works, the gas meter valve is on and, on a prepayment meter, there is credit. In freezing weather, check the plastic condensate pipe outside: if it is frozen, pour warm (not boiling) water along it. Then press reset once. If the code comes back, stop resetting.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the gas supply is fine and the code returns after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does L2 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, L2 is listed in the manufacturer's table as "Flame loss lockout (this manual lists L2 alongside F2 as flame loss)". Check another gas appliance works, the meter valve is on and any prepay meter has credit, then reset once. If it returns, book a Gas Safe registered engineer.
L6 Ideal Logic Combi
Engineer after one resetIgnition / flameWhat it means
False flame lockout: a flame was detected when there should not be one.
Likely causes
Flame detection electrode, wiring or the gas valve.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does L6 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, L6 is listed in the manufacturer's table as "False flame lockout: a flame was detected when there should not be one". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Water pressure / circulation
F1 Ideal Logic Combi
Safe checks firstWater pressure / circulationWhat it means
Low water pressure.
Likely causes
Water lost from the heating system through a leak, the pressure relief valve or bleeding radiators, or a flat expansion vessel.
What you can safely do
Look at the pressure gauge while the boiler is cold. If it is below about 1 bar, top it up with the filling loop exactly as your user guide shows, to about 1–1.5 bar or the figure in your guide, then close the loop fully. Check the radiator valves are open, then press reset once.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if you have to top up more than once every few months, the gauge goes above about 2.5 bar when hot, water drips from the outside overflow pipe, or the code returns after topping up.
What does F1 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F1 is listed in the manufacturer's table as "Low water pressure". With the boiler cold, check the pressure gauge; if it is below the level in your user guide, top it up as the guide shows, then reset once. If it returns, book a Gas Safe registered engineer.
Temperature / overheat
L1 Ideal Logic Combi
Engineer after one resetTemperature / overheatWhat it means
Flow temperature overheat or no water flow.
Likely causes
Low pressure, air, a stuck pump, closed valves or a blocked system.
What you can safely do
Let the boiler cool for 20 to 30 minutes, then press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Overheat shut-downs are safety devices doing their job, so this is engineer-only.
What does L1 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, L1 is listed in the manufacturer's table as "Flow temperature overheat or no water flow". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Flue / fan / air
F3 Ideal Logic Combi
Engineer after one resetFlue / fan / airWhat it means
Fan fault.
Likely causes
A failed fan, fan wiring or the control board.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the terminal looks clear and the code returns. Flue and fan faults can affect how combustion gases leave your home, so this is engineer-only.
What does F3 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F3 is listed in the manufacturer's table as "Fan fault". Likely causes include a failed fan, fan wiring or the control board. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Sensors / thermistors
F4 Ideal Logic Combi
Engineer after one resetSensors / thermistorsWhat it means
Flow thermistor fault.
Likely causes
Failed flow thermistor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does F4 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F4 is listed in the manufacturer's table as "Flow thermistor fault". Likely causes include failed flow thermistor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F5 Ideal Logic Combi
Engineer after one resetSensors / thermistorsWhat it means
Return thermistor fault.
Likely causes
Failed return thermistor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does F5 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F5 is listed in the manufacturer's table as "Return thermistor fault". Likely causes include failed return thermistor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F6 Ideal Logic Combi
Engineer after one resetSensors / thermistorsWhat it means
Outside sensor failure.
Likely causes
Faulty or disconnected outside weather sensor.
What you can safely do
Nothing urgent: the boiler normally keeps heating without the outdoor sensor, using a fixed setting. Press reset once to see if it clears.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does F6 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F6 is listed in the manufacturer's table as "Outside sensor failure". Likely causes include faulty or disconnected outside weather sensor. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
PCB / electrical
F7 Ideal Logic Combi
Safe checks firstPCB / electricalWhat it means
Low mains voltage.
Likely causes
Low supply voltage at the property. The manual says to contact an electrician or your electricity provider.
What you can safely do
Check whether lights are dimming or other appliances are struggling. If they are, contact an electrician or your electricity network operator (call 105 for a power cut). Then press reset once.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if your mains supply is fine and the code continues, so the boiler's own supply and board can be checked.
What does F7 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F7 is listed in the manufacturer's table as "Low mains voltage". Likely causes include low supply voltage at the property. The manual says to contact an electrician or your electricity provider. Reset once; if the code comes back, book a Gas Safe registered engineer and quote the full code. Do not open the casing.
F9 Ideal Logic Combi
Engineer after one resetPCB / electricalWhat it means
Unconfigured PCB.
Likely causes
A replacement board that has not been set up for this boiler.
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does F9 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, F9 is listed in the manufacturer's table as "Unconfigured PCB". Likely causes include a replacement board that has not been set up for this boiler. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
C0 Ideal Logic Combi
Engineer after one resetPCB / electricalWhat it means
BCC (boiler chip card) activation fault.
Likely causes
The boiler's configuration chip has not activated correctly.
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does C0 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, C0 is listed in the manufacturer's table as "BCC (boiler chip card) activation fault". Likely causes include the boiler's configuration chip has not activated correctly. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
C2 Ideal Logic Combi
Engineer after one resetPCB / electricalWhat it means
BCC (boiler chip card) fault.
Likely causes
Missing or faulty configuration chip.
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does C2 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, C2 is listed in the manufacturer's table as "BCC (boiler chip card) fault". Likely causes include missing or faulty configuration chip. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Other / controls
L5 Ideal Logic Combi
Safe checks firstOther / controlsWhat it means
Five boiler resets within 15 minutes. The boiler blocks further resets.
Likely causes
Repeated resetting of an underlying fault.
What you can safely do
Stop resetting. Switch the boiler off at its mains switch, wait at least 15 minutes, then check the gas supply and pressure before trying one more reset.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer now. Repeated resets mean an underlying fault is still there; tell them which code you were resetting.
What does L5 mean on an Ideal Logic Combi boiler?
On an Ideal Logic Combi, L5 is listed in the manufacturer's table as "Five boiler resets within 15 minutes". The boiler blocks further resets. Likely causes include repeated resetting of an underlying fault. Reset once; if the code comes back, book a Gas Safe registered engineer and quote the full code. Do not open the casing.
Common questions
About Ideal fault codes
3 questions
Which Ideal fault codes can I usually deal with myself?
On the Ideal ranges in our guide, only these codes have a safe homeowner check first: F2, L2 for gas supply or flame loss (check the meter and credit); F1 for low pressure (top up). Reset once afterwards. Every other code needs a Gas Safe registered engineer; never open the casing.
Where can I find the official fault code list for my Ideal Logic Combi?
Ideal lists the fault codes in the installation and servicing manual for the Logic Combi (document UIN 204626 A12 (January 2014)). Check your data badge matches this model first, because codes differ between ranges, and note the exact code before resetting.
Where can I find the official fault code list for my Ideal Logic Max Combi C?
Ideal publishes the fault table in the installation and servicing manual for the Logic Max Combi C (UIN 223440 A05, User's section 8). CombiCert's fault code guide explains 17 codes from it. Check your data badge matches this model first, because codes differ between ranges. Write down the exact code before resetting, so the engineer can diagnose it faster.
Codes by type: Ideal Logic Combi (24 / 30 / 35)
7 questions
Which Ideal Logic Combi fault code relates to the flue, fan or air supply?
On the Ideal Logic Combi, the manufacturer's table has one flue, fan or air supply code, F3. F3 is listed in the manufacturer's table as "Fan fault". This code has no homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Combi fault codes mean the boiler will not light or loses its flame?
On the Ideal Logic Combi, the manufacturer's table has 3 ignition or flame codes: F2, L2, L6. For F2, L2, first check the gas meter, prepay credit and another gas appliance, then reset once. The other code needs a Gas Safe registered engineer.
Which Ideal Logic Combi fault code relates to controls or other faults?
On the Ideal Logic Combi, the manufacturer's table has one controls or other code, L5. L5 is listed in the manufacturer's table as "Five boiler resets within 15 minutes". This code has no homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Combi fault codes point to a control board or electrical fault?
On the Ideal Logic Combi, the manufacturer's table has 4 control board or electrical codes: C0, C2, F7, F9. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Combi fault codes point to a temperature sensor fault?
On the Ideal Logic Combi, the manufacturer's table has 3 temperature sensor codes: F4, F5, F6. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Combi fault code means the boiler is overheating?
On the Ideal Logic Combi, the manufacturer's table has one overheat code, L1. L1 is listed in the manufacturer's table as "Flow temperature overheat or no water flow". This code has no homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Combi fault code relates to water pressure or circulation?
On the Ideal Logic Combi, the manufacturer's table has one water pressure or circulation code, F1. With the boiler cold, check the pressure gauge; if it is below the level in your user guide, top it up as the guide shows, then reset once. If it returns, book a Gas Safe registered engineer.
Codes by type: Ideal Logic Max Combi C (C24 / C30 / C35, IE edition manual)
7 questions
Which Ideal Logic Max Combi C fault code relates to the flue, fan or air supply?
On the Ideal Logic Max Combi C, the manufacturer's table has one flue, fan or air supply code, F3. F3 is listed in the manufacturer's table as "Fan fault". This code has no homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Max Combi C fault codes mean the boiler will not light or loses its flame?
On the Ideal Logic Max Combi C, the manufacturer's table has 3 ignition or flame codes: F2, L2, L6. For F2, L2, first check the gas meter, prepay credit and another gas appliance, then reset once. The other code needs a Gas Safe registered engineer.
Which Ideal Logic Max Combi C fault code relates to controls or other faults?
On the Ideal Logic Max Combi C, the manufacturer's table has one controls or other code, LC. LC is listed in the manufacturer's table as "Five boiler resets within 15 minutes". This code has no homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Max Combi C fault codes point to a control board or electrical fault?
On the Ideal Logic Max Combi C, the manufacturer's table has 3 control board or electrical codes: F7, F9, L9. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Max Combi C fault codes point to a temperature sensor fault?
On the Ideal Logic Max Combi C, the manufacturer's table has 6 temperature sensor codes: F4, F5, F6, FA, L4, L5. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Max Combi C fault code means the boiler is overheating?
On the Ideal Logic Max Combi C, the manufacturer's table has one overheat code, L1. L1 is listed in the manufacturer's table as "Flow temperature overheat or no water flow". This code has no homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Ideal Logic Max Combi C fault codes relate to water pressure or circulation?
On the Ideal Logic Max Combi C, the manufacturer's table has 2 water pressure or circulation codes: F1, FU. For F1, first check the pressure gauge when cold and top up if low, as your user guide shows, then reset once. The other code needs a Gas Safe registered engineer.
Code still showing? Book a repair
CombiCert Ltd is a Gas Safe registered business (621146) in Telford, Shropshire. Our team of 2 to 5 engineers is led by director and Gas Safe engineer Peter Jefferson. Boiler repair from £90 + VAT, parts quoted separately.
Send us the make, model and the exact code on WhatsApp and we will tell you what we need to check.
Explanations are written by CombiCert from the manufacturer manuals listed, which you should check for your exact model. This page is general information, not a diagnosis. If you smell gas, call 0800 111 999.