BoilerFaultCodes.com

Ideal Logic Code Combi ESP1 Fault Codes

Combi Natural Gas 26-38 kW 2013-present
GC Numbers: 47-348-7447-348-7547-348-76

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Most common fault codes

4.2
Your boiler has shut down because its internal temperature has become too high, often caused by a lack of water flow or a blockage.
May be DIY safe · £100-350
4.3
Your boiler has failed to light after several attempts, meaning it has shut down as a safety precaution and will not provide heating or hot water.
May be DIY safe · £100-£350
4.4
Your boiler has detected a flame when it shouldn't be there, which usually means a internal component is stuck open or there is a fault with the electronics.
Gas Safe engineer required · £180-350

All 117 fault codes

Code Severity Plain English
00 Low Your boiler is working perfectly fine and is simply waiting for you to turn up the thermostat or turn on a hot tap.
2S01 Low Your boiler is notifying you that it has been configured to be controlled by a single external timer or thermostat wire rather than a smart system.
2S02 Medium Your boiler is confused by how your heating controls are wired and thinks it should be receiving two different signals to turn on at once.
4.2 High Your boiler has shut down because its internal temperature has become too high, often caused by a lack of water flow or a blockage.
4.3 High Your boiler has failed to light after several attempts, meaning it has shut down as a safety precaution and will not provide heating or hot water.
4.4 Emergency Your boiler has detected a flame when it shouldn't be there, which usually means a internal component is stuck open or there is a fault with the electronics.
4.5 High Your boiler has detected that the water pressure inside the system is too low to run safely and has switched itself off.
4.6 High Your boiler is struggling to keep its flame lit, which means the system has safely shut down to prevent issues.
4.7 High Your boiler has stopped working because the internal fan, which safely clears exhaust fumes, is not running correctly.
4.8 High Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, preventing it from heating your home safely.
4.9 High Your boiler has detected an issue with the sensor that monitors the temperature of the water returning to the unit, likely causing it to shut down for safety.
4.10 Low Your boiler has lost communication with the sensor that monitors the outdoor temperature, which means it cannot automatically adjust its settings based on the weather.
4.11 High Your boiler has detected that the water pressure in the system is too low and needs to be topped up to work properly.
4.12 High Your boiler has stopped working because it cannot detect water moving through the internal pipes to keep the system safe.
4.13 High Your boiler's internal computer parts are failing to talk to each other, meaning the system cannot operate or provide heat and hot water.
4.14 High Your boiler is having trouble measuring the temperature of your hot water, which usually means it cannot heat water safely or effectively.
4.15 Medium Your boiler is heating your radiators normally, but it is failing to provide hot water when you turn on your taps.
4.16 High Your boiler has lost all power or the control screen has failed, meaning the system will not turn on or provide heat.
BLANK DISPLAY High Your boiler has no power or the screen has failed, meaning it cannot provide heating or hot water until the electrical supply is restored.
Blocked Flue/Condensate High Your boiler is unable to get rid of waste gases or waste water safely, which has caused it to shut down for protection.
C Low Your boiler is working normally and is currently providing heat to your radiators.
D Low Your boiler is working normally and is currently heating up water for your taps or shower.
DHW Thermistor Fault High Your boiler is struggling to accurately measure the temperature of your hot water, which typically means your taps will only run cold or have inconsistent heat.
dU Low Your boiler is currently set to a specific maintenance mode used by engineers to replace internal parts, rather than being in a fault state.
F High Your boiler has detected a specific internal fault and requires you to check the number following the 'F' on the display to identify the exact problem.
F 0A High Your boiler has detected that the water is flowing in the wrong direction through the pipes or that the temperature sensors have been installed on the wrong pipes.
F 0d High Your boiler is struggling to push water through the heating system, which usually means the pressure is too low or something is blocking the flow.
F 0t Medium Your boiler is having trouble communicating with your wall thermostat, meaning it doesn't know when to turn your heating on or off.
F 0U High Your boiler is overheating because the water is not flowing through the system quickly enough to be cooled down.
F 04 L 04 High Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, causing it to shut down as a safety precaution.
F 04 OR L 04 High Your boiler has detected a problem with the sensor that monitors the temperature of the water leaving the unit, meaning it cannot safely control the heat.
F 05 L 05 High Your boiler has detected a problem with the temperature sensor that monitors the water returning from your radiators, causing the system to shut down for safety.
F 05 OR L 05 High Your boiler has detected a problem with the sensor that monitors the temperature of the water returning to the unit, causing it to stop working for safety.
F 09 L 09 High Your boiler's internal computer has lost its programming or was replaced and hasn't been set up yet, meaning it doesn't know how to operate your specific heating system.
F0 d High Your boiler has detected that water is not moving through the system properly, which has caused it to stop working for safety.
F0U High Your boiler has sensed that the water getting sent out is significantly hotter than the water coming back, suggesting that water is not circulating through your system properly.
F1 High Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
F01 High Your boiler has lost water pressure, which prevents it from firing up to provide heating or hot water.
F2 High Your boiler has started to light but the flame has gone out, which means the system has stopped providing heating and hot water for safety.
F02 High Your boiler has started an ignition process successfully but then lost the flame, meaning it cannot stay lit to provide heat or hot water.
F3 High Your boiler has detected an issue with the fan that pushes exhaust gases out of your home, causing the system to shut down for safety.
F03 High Your boiler has stopped working because the fan that removes waste gases is not spinning correctly, causing the system to shut down for safety.
F4 High Your boiler has detected an issue with the sensor that measures the temperature of the water leaving the unit, preventing it from heating your home safely.
F04 High Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, which means it cannot heat your home or water safely.
F04 L04 High Your boiler has detected a problem with the sensor that monitors the temperature of the water leaving the unit, usually causing the system to shut down as a safety precaution.
F5 High Your boiler has detected an issue with the sensor that monitors the temperature of the water returning from your radiators.
F05 High Your boiler has detected a problem with the sensor that monitors the temperature of the water returning to the unit, causing it to stop working for safety.
F05 L05 High Your boiler has detected a problem with the sensor that monitors the temperature of the water coming back from your radiators, preventing it from heating up correctly.
F6 Low Your boiler is having trouble communicating with the temperature sensor located on the outside of your house, which helps it decide how hard to work based on the weather.
F06 Low Your boiler's outdoor temperature monitor is not sending a signal, which may cause your heating to behave unpredictably based on the weather.
F7 High Your boiler has stopped working because the electrical power coming into your home is at a lower voltage than it needs to operate safely.
F07 High Your boiler has detected that the electrical supply from the grid is currently too low for it to operate safely.
F8 High Your boiler's main internal computer has lost its settings or has developed an internal electrical fault, preventing it from starting.
F9 High Your boiler’s internal control board has lost its configuration or is brand new and hasn't been programmed yet to tell it which model it is.
F09 High Your boiler's internal computer has developed a fault and can no longer control the heating or hot water safely.
F09 L09 High Your boiler's main control board has lost its programmed settings and no longer knows how to operate the specific model it is installed in.
F10 High Your boiler is unable to create the electric spark needed to light the gas burner, meaning your heating and hot water will not work.
F12 High Your boiler's internal pump has stopped spinning, which means hot water cannot be moved around the system to heat your home or taps.
F13 High Your boiler has stopped working because the internal pump that moves water around your heating system has failed or cannot communicate with the control board.
F14 High Your boiler has detected that the electricity supply coming into your home is at a dangerously high voltage, which could damage the internal electronics.
F15 High Your boiler has stopped working because the internal pump that moves hot water around your pipes has developed an electrical fault or has failed.
F16 High Your boiler has detected an internal electrical problem with the gas control valve, meaning it cannot safely ignite to provide heating or hot water.
F17 High Your boiler has detected that the internal pump, which moves water around your pipes and radiators, is not working correctly.
FA High Your boiler has detected that the temperature sensors for the water going in and out are reporting incorrect or swapped readings, which has caused the system to shut down for safety.
Fan Fault High Your boiler has detected a problem with the fan that clears exhaust gases, preventing the system from starting up for safety reasons.
FL Low Your boiler is accidentally trying to use a feature it doesn't have, which is usually caused by a minor electronic glitch or a recent settings change.
Flame On Before Gas On Emergency Your boiler's safety sensor detects a flame before the gas valve has even been told to open, which usually means a internal component is stuck or sending a false signal.
Flame On Before Gas Valve On High Your boiler's safety system has detected a flame signal when there shouldn't be one, which prevents the unit from starting up for safety reasons.
FLOW TEMPERATURE SETPOINT CANNOT BE INCREASED TO 80ºC Low Your boiler's maximum temperature setting has been restricted in the hidden installer menu, preventing it from reaching its full heating potential.
Flow Thermistor Fault High Your boiler has detected that a temperature sensor is not communicating correctly, which has caused the system to stop working to prevent overheating.
Fn High Your boiler has lost its flame while trying to run, which means it cannot heat your water or your radiators.
FP Low Your boiler has detected that the temperature is very low and has automatically turned itself on to prevent the internal pipes from freezing.
FU High Your boiler has detected that heat is building up too quickly and cannot circulate around your home, likely due to a blockage or a pump failure.
Gas Valve Fault High Your boiler has detected an electrical issue with the gas control system and has shut down as a safety precaution.
L High Your boiler has stopped working and locked itself to prevent damage, but it needs a second digit to identify the specific problem.
L 0C High Your boiler is repeatedly shutting down and trying to restart itself, likely due to an underlying component failure preventing reliable ignition.
L 0d High Your boiler has stopped working because it cannot safely get rid of exhaust fumes or waste water, often due to a blockage or a frozen pipe.
L0 High Your boiler has stopped working because either its exhaust pipe is obstructed or the pipe that drains away waste water is blocked.
L0C High Your boiler has been manually reset too many times in a short window of time and has locked itself out as a safety precaution.
L0d High Your boiler has stopped working because the pipe that carries water away from the unit is likely frozen or blocked, which you might have noticed as a gurgling sound.
L1 High Your boiler has switched itself off because the internal water temperature has become too hot, usually caused by a lack of water flow through the system.
L01 High Your boiler has switched itself off because internal sensors have detected it is getting too hot, which is a safety measure to prevent damage.
L2 High Your boiler has tried to light several times but cannot establish a flame, meaning it has shut down for safety to prevent gas build-up.
L02 High Your boiler has failed to light several times and has locked itself for safety, meaning you have no heating or hot water.
L4 High Your boiler has sensed a problem with the internal thermometer that monitors the water temperature leaving the unit, causing it to shut down for safety.
L04 High Your boiler has detected a problem with the internal sensor that monitors the temperature of the water leaving the unit, causing it to stop working for safety.
L5 High Your boiler has stopped working because a sensor that monitors the temperature of the water coming back into the unit has detected a problem or failed.
L05 High Your boiler has lost its ability to accurately measure the temperature of the water coming back into the system, which is preventing it from heating up correctly.
L6 High Your boiler thinks it sees a flame even though it hasn't tried to light yet, causing it to shut down as a safety precaution.
L06 High Your boiler is detecting a flame even though the gas valve should be closed, which is a safety precaution that stops the boiler from running.
L8 High Your boiler's main internal computer has lost its settings or has developed an internal electrical fault, preventing it from starting.
L9 High Your boiler's main internal computer has lost its settings or has developed an internal electrical fault, preventing it from starting.
L09 High Your boiler's internal computer brain is not communicating correctly with the rest of the unit and needs to be officially set up.
LC High Your boiler has attempted to restart itself too many times in a short period because it is detecting a recurring problem.
Ln High Your boiler has lost its flame while running, meaning it is not getting enough gas or the spark is failing to keep the burner lit.
LO2 High Your boiler is likely unable to drain away the condensation it produces naturally, causing it to 'choke' and shut down.
No CH Operation But DHW Works OK Medium Your boiler is providing hot water to your taps correctly, but the central heating is not turning on for your radiators.
No DHW But CH Works OK Medium Your boiler is working to heat your radiators, but it is failing to detect when you turn on a hot tap or is unable to switch the water flow to your taps.
No Water Flow High Your boiler has stopped working because it cannot detect water moving through the pipes properly.
oF Low Your boiler is currently updating its internal settings and is showing this code to indicate it has been reset during its configuration process.
Outside Sensor Fault Low Your boiler is struggling to understand the outdoor temperature, which might make your heating feel less efficient or slightly inconsistent.
P1 Low Your boiler is displaying a service setting notification to run the pump at maximum speed, which usually indicates an installation or maintenance mode rather than a dangerous mechanical failure.
P7 Low Your boiler is displaying a configuration message regarding how fast its internal pump should run to move water through your radiators.
PCB Fault High Your boiler's main internal computer has developed a serious glitch or hardware failure, meaning the unit cannot safely manage its functions.
PCB REPLACED High Your boiler has recently had its main circuit board changed and simply needs a quick reset to finish the setup process.
PH Low Your boiler is not broken; it is simply in 'Installer Mode' which is used during setup or testing and can be exited by adjusting the control knobs.
Return Thermistor Fault High Your boiler is struggling to monitor the temperature of the water returning from your radiators, which prevents it from heating your home or water efficiently.
Room Thermostat Fault High Your boiler has lost communication with your heating controls, meaning your radiators might not turn on when you want them to.
SE Low Your boiler is simply reminding you that its annual service is due soon; it is a notification rather than a breakdown.
SERVICE DUE Low Your boiler is working correctly, but it has reached its annual anniversary and is reminding you that a routine safety check and service are now required.
SH Low Your boiler is currently in a manual testing mode where it runs at full power, usually activated by a technician during a service.
SL Low Your boiler is currently in a manual service mode used for testing and is not experiencing an actual fault.
Spare PCB Not Set High Your boiler's main control board has been replaced or reset but hasn't been programmed with the specific settings required to run your heating and hot water.
U Low Your boiler is currently set to a maintenance mode used by engineers to check the internals and is not in its normal operating state.
UF Low Your boiler is currently stuck in a professional service mode used by engineers when they are replacing an internal valve.
uP Low Your boiler has detected that it was turned on while its internal computer chip was being replaced or updated.
VF Low Your boiler is currently running a self-cleaning cycle to remove air bubbles from the pipes and will return to normal operation shortly.

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