Ideal HP290 Fault codes & diagnostics

113 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Heat Pump Natural Gas 9 kW 2023-present

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108 High 4 Medium 1 Low

All 113 documented codes

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9.1.2

Your heat pump has stopped working because water is not circulating correctly through the outdoor unit.

High DIY-safe £120-350

What to check first

  1. Check that your central heating system pressure is between 1.0 and 1.5 bar
  2. Ensure all radiator valves and external isolation valves are fully open
  3. Check the outdoor unit for any debris or ice blocking the area
  4. Reset the system at the control panel

Parts commonly replaced

  • Circulation Pump
  • Flow Switch
  • Magnetic System Filter

Related codes

9.1.3

Your boiler has detected that its electrical power wires have been connected in the wrong order, preventing it from starting up safely.

High Engineer only £80-160

Parts commonly replaced

  • Electrical wiring (rewiring internal or external terminals)
  • Printed Circuit Board (PCB) if damaged by polarity reversal

Related codes

9.1.4

Your heat pump's external unit is unable to talk to the control panel inside your home, meaning the system cannot receive instructions to provide heating or hot water.

High Engineer only £180-450

Parts commonly replaced

  • Communication cable
  • Outdoor PCB
  • User Interface controller

Related codes

9.1.5

Your system has a faulty temperature sensor in the main pipework, which means it cannot accurately monitor the water heat flowing through your home.

High Engineer only £120-£200

Parts commonly replaced

  • Header Thermistor (T1 Sensor)
  • Thermistor Wiring Harness

Related codes

9.1.6

Your heat pump has stopped providing hot water because a sensor that monitors the water temperature has developed a fault or is disconnected.

High Engineer only £140-£220

Parts commonly replaced

  • DHW Cylinder Thermistor (T5)
  • Thermistor Wiring Harness
  • Main PCB

Related codes

9.1.7

Your heating system is having trouble measuring the temperature for your second heating area, which often means that specific zone won't warm up correctly.

Medium Engineer only £120-£200

Parts commonly replaced

  • NTC Thermistor Sensor
  • Wiring Harness

Related codes

9.1.8

Your outdoor heat pump unit has detected a fault with a temperature sensor that monitors the air passing through it, which may cause the system to stop working correctly.

High Engineer only £160-£320

Parts commonly replaced

  • Outdoor Heat Exchanger Thermistor (T3)
  • Sensor Wiring Loom
  • Main PCB

Related codes

9.1.9

Your heat pump has stopped working because water is not moving through the outdoor unit properly.

High DIY-safe £120-350

What to check first

  1. Check that your central heating pressure gauge is between 1 and 1.5 bar
  2. Ensure all radiator valves and isolation valves are fully open
  3. Check the outdoor unit for any obvious obstructions or debris

Parts commonly replaced

  • Circulation pump
  • Water flow sensor
  • Magnetic system filter (cleaning or replacement)

Related codes

9.1.10

Your heat pump's outdoor unit has detected a problem with a temperature sensor that monitors the cooling fluid, preventing the system from heating your home efficiently.

High Engineer only £180-350

Parts commonly replaced

  • Refrigerant Return Thermistor
  • Wiring Harness
  • Main PCB

Related codes

9.1.11

Your heat pump's outdoor unit has detected a problem with the sensor that monitors the temperature of the refrigerant gas as it leaves the compressor, causing the system to stop running to prevent damage.

High Engineer only £180-£320

Parts commonly replaced

  • Discharge Pipe Thermistor
  • Wiring Harness
  • Main PCB

Related codes

Showing 11–20 of 113
9.1.12

Your heat pump has stopped working because a sensor that measures the water temperature returning from your home has developed a fault.

High Engineer only £140-£260

Parts commonly replaced

  • Return Water Temperature Thermistor (Tw_In)
  • Sensor Clip/Housing
  • Control PCB

Related codes

9.1.13

Your indoor and outdoor units are failing to speak to each other, meaning your central heating and hot water have stopped working.

High Engineer only £180-450

Parts commonly replaced

  • Outdoor PCB
  • Indoor PCB
  • Data Communication Cable

Related codes

9.1.28

Your heat pump has stopped working because a sensor detected that the internal system is getting too hot, likely due to a lack of proper airflow or low refrigerant levels.

High Engineer only £150-450

Parts commonly replaced

  • Refrigerant
  • Electronic Expansion Valve (EEV)
  • Discharge Temperature Sensor
9.1.29

Your heat pump has stopped working because it cannot accurately monitor the water pressure in the system.

High Engineer only £180-290

Parts commonly replaced

  • Low pressure sensor
  • Sensor wiring harness

Related codes

9.1.30

Your boiler has stopped working because its internal pressure sensors have been plugged into the wrong sockets during a service or repair.

High Engineer only £80-140

Parts commonly replaced

  • Wiring harness
  • Pressure sensor

Related codes

9.1.31

Your heat pump has stopped because the refrigerant gas is getting too hot, likely due to a blockage or restricted water flow through the system.

High DIY-safe £120-350

What to check first

  1. Check that all your radiators are turned on and the valves are open.
  2. Ensure the external unit is clear of leaves, debris, or snow.
  3. Try resetting the unit at the control panel to see if the fault clears.

Parts commonly replaced

  • Circulation pump
  • Magnetic system filter (cleaning)
  • Temperature sensor (thermistor)

Related codes

9.1.34

Your heat pump's engine has stopped running because it is struggling to start or has an electrical fault, meaning you have no heating or hot water.

High Engineer only £600-£1,800

Parts commonly replaced

  • Compressor
  • Inverter PCB
  • Start Capacitor

Related codes

9.1.35

Your boiler is unable to switch between heating your house and providing hot water because an internal diverter component is stuck or broken.

High Engineer only £180-£320

Parts commonly replaced

  • 3-Way Diverter Valve Actuator
  • Diverter Valve Internal Cartridge
  • Wiring Harness

Related codes

9.1.36

Your heat pump’s automatic high-temperature disinfection cycle for your hot water tank failed to complete as scheduled.

Medium DIY-safe £0-120

What to check first

  1. Check that your hot water cylinder immersion heater switch is turned on and hadn't tripped.
  2. Ensure hot water schedule allows enough time for the tank to reach 60-65°C.
  3. Restart the heat pump control panel to clear the temporary warning.

Parts commonly replaced

  • Immersion heater element
  • Cylinder temperature sensor
  • Immersion heater relay

Related codes

9.1.37

Your heating cannot circulate around your home because the main pump has stopped working or is not responding.

High Engineer only £220-450

Parts commonly replaced

  • Central Heating Pump
  • Pump Wiring Harness
  • Main PCB

Related codes

Showing 21–30 of 113
C7

Your boiler’s internal electronic brain is having trouble communicating with the compressor pump, meaning your heating and hot water have stopped working.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Main Control PCB
  • Compressor Wiring Harness
E0

Your heat pump has stopped working because water isn't flowing through the outdoor unit properly, and it has failed to start ten times in a row.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the system pressure gauge is between 1.0 and 1.5 bar
  3. Look for any external valves on the pipework that might be closed
  4. Clear any debris or blockages from around the outdoor unit fans

Parts commonly replaced

  • Circulation pump
  • Water flow switch
  • Magnetic system filter (cleaned or replaced)

Related codes

E01

Your heat pump has stopped working because the internal safety system has detected a communication error or a power supply issue.

High Engineer only £150-£400

Parts commonly replaced

  • Main PCB
  • Communication Cable
  • Control Board
E1

Your boiler has detected that the electrical wiring coming from your home’s power supply matches the wrong terminals, meaning the power flow is backwards.

High Engineer only £80-160

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

E2

Your indoor control panel has lost communication with the outdoor unit, meaning your heat pump cannot receive instructions to provide heating or hot water.

High Engineer only £150-450

Parts commonly replaced

  • Communication Cable
  • Outdoor PCB
  • User Interface Panel

Related codes

E3

Your system's main temperature sensor is sending incorrect information, which means your heating might not work efficiently or at all.

High Engineer only £120-£220

Parts commonly replaced

  • Header Thermistor (T1)
  • Connecting Wiring Loom
  • Control PCB

Related codes

E4

Your heat pump has stopped making hot water because the sensor that monitors your cylinder's temperature is no longer communicating correctly.

High Engineer only £140-£260

Parts commonly replaced

  • DHW Cylinder Thermistor (NTC Sensor)
  • Sensor Wiring Harness

Related codes

E5

Your heat pump has stopped working because one of its outdoor temperature sensors is sending an incorrect or missing signal to the main control board.

High Engineer only £180-290

Parts commonly replaced

  • T3 Thermistor (Sensor)
  • Sensor Wiring Harness
  • Outdoor Main PCB

Related codes

E6

Your heat pump's external temperature sensor is giving a faulty reading, which means the system cannot accurately adjust the heating based on the weather outside.

Medium Engineer only £140-£260

Parts commonly replaced

  • Outdoor ambient temperature sensor (T4)
  • Sensor wiring harness
  • Main PCB

Related codes

E8

Your boiler has stopped working because water is not moving through the system properly or the pressure is too low.

High DIY-safe £100-£350

What to check first

  1. Check that the boiler pressure gauge is between 1 and 1.5 bar
  2. If the pressure is low, use the filling loop to top it up
  3. Ensure all radiator valves and boiler isolation valves are fully open
  4. Reset the boiler once the pressure is corrected

Parts commonly replaced

  • Circulation Pump
  • Water Pressure Sensor
  • Flow Thermistor

Related codes

Showing 31–40 of 113
E9

Your heat pump has stopped working because a sensor that monitors the temperature of the cooling liquid returning to the main unit has developed a fault.

High Engineer only £180-320

Parts commonly replaced

  • Refrigerant Return Thermistor (NTC Sensor)
  • Wiring Harness
  • Main Control PCB

Related codes

EA

Your heat pump has stopped working because a sensor that monitors the temperature of the outgoing refrigerant gas is reporting an incorrect or faulty reading.

High Engineer only £140-£260

Parts commonly replaced

  • Discharge Thermistor (NTC Sensor)
  • Wiring harness / Connector
  • Main PCB

Related codes

Ed

Your heat pump has stopped working because a sensor that monitors the temperature of the water returning to the outdoor unit has failed or detected an error.

High Engineer only £140-£260

Parts commonly replaced

  • Return Water Thermistor
  • Wiring Harness
  • Main PCB

Related codes

F1

Your heat pump's internal computer system has encountered an electrical problem and has stopped working to protect itself.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness
Fan Error

Your boiler has stopped working because the internal fan, which safely exhausts gases, is not spinning at the correct speed.

High Engineer only £280-450

Parts commonly replaced

  • Fan Assembly
  • Main PCB
  • Venturi Tube

Related codes

FC1

Your heat pump's outdoor sensor that monitors temperature change is not reporting correctly, which prevents the system from managing heat exchange properly.

High Engineer only £180-£320

Parts commonly replaced

  • Air-to-refrigerant outlet thermistor
  • Wiring harness
  • Main PCB
H0

Your indoor and outdoor units are failing to speak to each other, which has caused your heating system to stop working.

High Engineer only £120-450

Parts commonly replaced

  • Communication cable
  • Outdoor PCB
  • Indoor PCB

Related codes

H1

Your heat pump has stopped working because the internal control computers are unable to talk to each other.

High Engineer only £180-£550

Parts commonly replaced

  • Inverter PCB
  • Outdoor Main PCB
  • Communication Wiring Harness

Related codes

H2

Your heat pump has stopped working because a sensor that monitors the temperature of the internal heating fluid has developed a fault.

High Engineer only £140-£260

Parts commonly replaced

  • Refrigerant Thermistor (T2)
  • Sensor wiring harness
  • Main PCB

Related codes

H3

Your heat pump has detected a problem with a temperature sensor inside the unit, causing the system to stop working to prevent any damage.

High Engineer only £180-£350

Parts commonly replaced

  • Refrigerant Thermistor (T2B)
  • Sensor Wiring Harness
  • Main PCB

Related codes

Showing 41–50 of 113
H4

Your heat pump has stopped working because its internal electrical system has detected repeated power surges or excessive electrical demand.

High Engineer only £450-900

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • External Inverter Module

Related codes

H6

Your boiler has stopped working because the internal fan, which safely exhausts gases from the unit, is not spinning correctly.

High Engineer only £250-£450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
H7

Your boiler has detected that the electricity supply from the mains is either too high or too low for it to operate safely.

High Engineer only £150-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Surge Protector

Related codes

H8

Your heat pump has stopped working because it has detected an issue with a internal sensor that monitors the pressure levels within the system.

High Engineer only £130-240

Parts commonly replaced

  • High pressure sensor
  • Wiring harness
  • Main PCB

Related codes

H9

Your boiler is having trouble monitoring the temperature for your second heating zone, which may prevent that specific area of your home from warming up properly.

Medium Engineer only £90-180

Parts commonly replaced

  • Zone 2 Thermistor (NTC sensor)
  • Wiring harness / connector

Related codes

HA

Your heat pump has stopped because a sensor that measures the temperature of the water leaving the outdoor unit is giving an incorrect reading.

High Engineer only £160-280

Parts commonly replaced

  • Flow Thermistor
  • Wiring Harness
  • Control PCB

Related codes

Hb

Your heating system has shut down because it is struggling to circulate water properly while detecting very cold temperatures within the unit.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the system pressure is between 1 and 1.5 bar
  3. Check for any frozen external condensate or heat pump pipes

Parts commonly replaced

  • Circulation Pump
  • Flow/Return Thermistors
  • System Filter

Related codes

Hd

Your main heat pump unit is unable to talk to the secondary unit, meaning the system cannot coordinate properly to heat your home.

High Engineer only £120-350

Parts commonly replaced

  • Communication cable
  • PCB (Control Board)
  • Bus connector

Related codes

HF

Your heat pump's internal computer chips are not communicating correctly because their configuration settings do not match each other.

High Engineer only £120-350

Parts commonly replaced

  • Inverter PCB
  • Outdoor Main PCB

Related codes

High Pressure Sensor Error

Your heat pump has stopped working because its internal safety sensor has detected that the water pressure is too high, causing the system to shut down for protection.

High Engineer only £180-350

Parts commonly replaced

  • High Pressure Sensor
  • Pressure Relief Valve
  • Expansion Vessel

Related codes

Showing 51–60 of 113
Inverter High Current

Your heat pump has stopped because its internal electronics are detecting a power surge or a motor that is working too hard.

High Engineer only £350-£900

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Internal Wiring Harness
J2E

Your heat pump's internal electrical cooling system has become too hot and has shut down to prevent permanent damage.

High Engineer only £250-£650

Parts commonly replaced

  • Inverter PCB
  • Inverter cooling fan
  • Thermal paste/heatsink
J3E

Your heat pump has stopped working because the internal computer responsible for powering the compressor has detected a technical fault.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • IPM Module
  • Main Control Board

Related codes

J5E

Your heat pump’s main engine has encountered a problem and has stopped running to protect the system.

High Engineer only £350-1,200

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Harness
J6E

Your heat pump’s internal power control system has encountered an electrical fault, preventing the unit from heating your home.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • IPM Module

Related codes

J11

Your heat pump's internal motor system is drawing too much electricity, causing the unit to shut down to protect its electrical components.

High Engineer only £350-£900

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Power Module

Related codes

J12

Your heat pump's engine is drawing too much electrical power, causing the system to shut down to protect its internal circuits.

High Engineer only £350-£850

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Fan Motor
J31

Your heat pump's internal control system has detected an electrical communication error or a fault with the motor drive board.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring harness

Related codes

J32

Your heat pump's internal computer system has detected a communication or power issue with the motor control unit, causing the system to stop working for safety.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness

Related codes

J43

Your heat pump's internal control board has detected a communication or electrical fault with the motor that drives the system, meaning it cannot currently provide heating.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Internal Wiring Harness
Showing 61–70 of 113
J45

Your boiler has stopped working because it detects that the internal fan is the incorrect model for this specific unit.

High Engineer only £250-450

Parts commonly replaced

  • Fan Assembly
  • Main PCB
J46

Your heat pump’s internal power control system has encountered a fault, meaning the outdoor unit cannot currently run to provide heating or hot water.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness

Related codes

J47

Your heat pump's internal power control system has encountered a fault, meaning the outdoor unit cannot communicate properly with the compressor to provide heating or hot water.

High Engineer only £450-850

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness
J52

Your heat pump's engine has stopped turning unexpectedly, which means the system cannot currently generate heat for your home.

High Engineer only £350-900

Parts commonly replaced

  • Compressor
  • Inverter PCB
  • Start Capacitor
J61

Your boiler has detected an electrical fault with the internal fan, which is preventing the unit from starting up for safety reasons.

High Engineer only £250-450

Parts commonly replaced

  • Fan assembly
  • Fan wiring harness
  • Main PCB
J65

Your heat pump has stopped working because the internal computer that controls the motor has detected an electrical problem.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Harness
L1E

Your heat pump's internal power system is detecting an electrical surge or overload, causing the unit to shut down to prevent damage.

High Engineer only £350-£900

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Power cable

Related codes

L2E

Your heat pump has stopped working because its internal electrical cooling system has become too hot.

High DIY-safe £150-£600

What to check first

  1. Check that the outdoor unit is not covered by leaves, snow, or debris
  2. Ensure there is at least a one-metre clear space around the outdoor unit for airflow
  3. Turn the power supply to the heat pump off and back on again to attempt a reset

Parts commonly replaced

  • Inverter PCB
  • Inverter cooling fan
  • Thermal paste

Related codes

L3E

Your heat pump's internal control board is experiencing an electrical communication problem and cannot operate the compressor.

High Engineer only £450-£950

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Compressor Assembly

Related codes

L5E

Your heat pump’s main engine is struggling to pull enough power to start up correctly.

High Engineer only £250-800

Parts commonly replaced

  • Start Capacitor
  • Inverter PCB
  • Compressor

Related codes

Showing 71–80 of 113
L6E

Your heat pump has stopped working because the internal computer that controls the speed of the motor has detected an electrical fault.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Harness
L11

Your heat pump has shut down because a specific part of its motor or power electronics is drawing too much electricity.

High Engineer only £350-£900

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Power IPM Module
L12

Your heat pump has shut down because a power component is drawing too much electricity, likely due to a blockage or a part wearing out.

High Engineer only £350-950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Inverter Filter Board

Related codes

L31

Your heat pump's internal control computer has detected an electrical fault with the unit that powers the motor, preventing it from running.

High Engineer only £650-£1,100

Parts commonly replaced

  • Inverter PCB
  • IPM Module
  • Main Control Board

Related codes

L32

Your heat pump has encountered a problem with its internal power management system, meaning it cannot currently run the compressor to provide heat.

High Engineer only £450-£950

Parts commonly replaced

  • Inverter PCB
  • IPM Module
  • Compressor wiring loom

Related codes

L34

Your heat pump’s internal computer system has detected an electrical communication problem, causing the unit to shut down to prevent damage.

High Engineer only £350-£900

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness

Related codes

L43

Your heat pump has stopped working because its internal computer board is having trouble communicating with the compressor system.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Loom
L45

Your boiler has identified that the internal fan is incompatible or incorrectly configured, causing the system to shut down for safety.

High Engineer only £280-450

Parts commonly replaced

  • Fan Assembly
  • Printed Circuit Board (PCB)
L46

Your heat pump's internal computer system has detected a communication or electrical issue with the power supply that controls the compressor.

High Engineer only £350-£850

Parts commonly replaced

  • Inverter PCB
  • Compressor Power Cable
  • Main Control Board

Related codes

L47

Your heat pump has stopped working because the internal power control system has detected an electrical fault.

High Engineer only £450-900

Parts commonly replaced

  • Inverter Drive Board
  • Inverter Power Module
  • Compressor

Related codes

Showing 81–90 of 113
L52

Your heat pump’s engine has stopped unexpectedly and is unable to restart, meaning your heating and hot water will likely stop working.

High Engineer only £250-£900

Parts commonly replaced

  • Compressor
  • Inverter PCB
  • Start Capacitor
L61

Your heat pump has detected an electrical fault within the wiring or the motor that drives the system, causing it to shut down to prevent damage.

High Engineer only £350-£900

Parts commonly replaced

  • Compressor
  • Wiring Loom
  • Inverter PCB
L65

Your heat pump has stopped working because of a communication or electrical issue within its internal power control unit.

High Engineer only £450-£950

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness
LB7

Your heat pump’s internal power management system has encountered an electrical fault, causing the unit to stop running to protect itself.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Compressor Power Cable
  • Main Control Board
LBC

Your heat pump's internal motor controller has encountered an electrical problem and has stopped working to protect the system.

High Engineer only £450-£950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Harness
LBE

Your heat pump has detected a pressure level that is too high within the system and has shut down to prevent damage.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure there are no external debris or plants blocking the airflow to the outdoor unit
  3. Check that the internal central heating valves (usually near the cylinder) are in the open position

Parts commonly replaced

  • High pressure switch
  • Circulation pump
  • Refrigerant pressure sensor
LC1

Your heat pump has stopped working because its internal computer board is having trouble communicating with the motor that runs the system.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Compressor

Related codes

LC2

Your heat pump has stopped working because of an internal electrical communication fault between the main control board and the motor.

High Engineer only £450-£950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Main Control Board

Related codes

LC3

Your heat pump has stopped working because of an internal electrical communication issue within its power control system.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness

Related codes

LC4

Your boiler has detected an internal electrical communication problem with the system that controls the pump and fan, meaning the unit cannot run safely.

High Engineer only £350-£700

Parts commonly replaced

  • Inverter Drive Board
  • Inverter Power Cable
  • Main PCB

Related codes

Showing 91–100 of 113
LC5

Your heat pump has stopped working because of a communication or electrical fault in the main power control unit.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Power Module
  • Main Control Board

Related codes

LC6

Your heat pump has stopped working because its internal computer board is having trouble communicating with or powering the compressor.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Harness

Related codes

LC7

Your heat pump has encountered a communication or power issue within its internal electrical control system, meaning it cannot currently heat your home.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness

Related codes

LC8

Your heat pump has stopped working because its internal power management system has detected an electrical fault.

High Engineer only £450-£900

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Loom

Related codes

LC9

Your heat pump’s internal power electronics have become too hot and have shut the system down to prevent damage.

High DIY-safe £150-450

What to check first

  1. Check that the outdoor unit is not covered or its air vents blocked by leaves or debris.
  2. Ensure there is at least a one-metre clear space around the outdoor unit for proper airflow.
  3. Turn the power to the unit off at the isolator switch, wait 5 minutes, and turn it back on to see if the code clears once cooled.

Parts commonly replaced

  • Inverter PCB
  • Inverter cooling fan
  • Heatsink

Related codes

LCA

Your heat pump has detected an electrical overload in the motor system and has shut down to protect its internal circuits.

High Engineer only £450-£950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Wiring Harness

Related codes

LCB

Your heat pump has encountered a communication or power issue with the internal electronics that manage the motor, causing the system to stop working.

High Engineer only £450-£950

Parts commonly replaced

  • Inverter PCB
  • Main Control Board
  • Wiring Harness

Related codes

LCD

Your heat pump has stopped working because of a communication or electrical issue within the internal power control system.

High Engineer only £350-£850

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Power Cable Harness
LCE

Your heat pump has stopped working because the internal power system has detected an electrical surge or overload.

High Engineer only £450-950

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Fan Motor
Low Pressure Error

Your boiler has detected that there is not enough water in the system to operate safely, causing it to shut down to prevent damage.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (a flexible silver hose) underneath or near the boiler.
  2. Open the one or two taps on the loop slowly until you hear water flowing.
  3. Watch the pressure gauge until it reaches 1.5 bar, then close the taps tightly.
  4. Press the Reset button on the boiler display to clear the error.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Expansion vessel

Related codes

Showing 101–110 of 113
Overcurrent Protection Error

Your heat pump has detected an electrical surge or heavy workload and has shut down to protect its internal motor and electronics.

High Engineer only £250-750

Parts commonly replaced

  • Inverter Board
  • Compressor
  • Fan Motor

Related codes

P0

Your boiler has detected that the water pressure is too low for it to operate safely, which usually means the system needs more water.

High DIY-safe £0-120

What to check first

  1. Locate the metal braided filling loop underneath or near the boiler
  2. Open the valves slowly until you hear water flowing and the pressure gauge reaches 1.5 bar
  3. Close both valves tightly and reset the boiler

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure sensor

Related codes

P1

Your heat pump has detected that the internal pressure is too high and has shut down to protect its internal components.

High DIY-safe £120-350

What to check first

  1. Ensure all radiator valves and zone valves are fully open to allow water to flow.
  2. Check that your external heating filters (like a magnetic filter) are not blocked with debris.
  3. Restart the unit to see if the fault clears after checking the water flow.

Parts commonly replaced

  • High Pressure Switch
  • Circulation Pump
  • Plate Heat Exchanger

Related codes

P3

Your heat pump has stopped working because its internal electrical circuit has detected a power surge or is drawing too much electricity to protect itself from damage.

High Engineer only £250-£650

Parts commonly replaced

  • Inverter PCB
  • Compressor
  • Fan Motor

Related codes

P4

Your heat pump has stopped working because its internal system is getting too hot, usually due to a lack of water flow or a refrigerant issue.

High DIY-safe £150-500

What to check first

  1. Check that all radiator valves and zone valves are fully open
  2. Ensure the external unit is clear of leaves, debris, or snow blocking airflow
  3. Check your system pressure gauge and top up to 1.5 bar if it is too low

Parts commonly replaced

  • Circulation pump
  • Discharge temperature sensor
  • Expansion valve

Related codes

P5

Your boiler has detected that water is struggle to circulate through your heating system quickly enough, often due to a blockage or a pump issue.

High DIY-safe £120-£350

What to check first

  1. Ensure all radiator valves (TRVs) are turned to the highest setting
  2. Check that the boiler pressure is between 1 and 1.5 bar
  3. Bleed all radiators to remove trapped air from the system

Parts commonly replaced

  • Circulation pump
  • Central heating filter
  • Flow/Return thermistors

Related codes

P21

Your boiler has stopped working because it cannot accurately tell if there is enough water pressure in the system to operate safely.

High Engineer only £120-£220

Parts commonly replaced

  • Water Pressure Sensor
  • Sensor Wiring Harness
  • Main PCB

Related codes

P27

Your boiler's internal wiring has been connected incorrectly, causing it to confuse high and low pressure readings.

High Engineer only £80-160

Parts commonly replaced

  • Wiring harness
  • Pressure sensor connector

Related codes

Pb

Your heat pump has temporarily paused its operation to prevent internal components from freezing during extremely cold weather.

Low DIY-safe

What to check first

  1. Check that the outdoor unit is clear of snow, ice, or leaf debris
  2. Ensure the airflow around the outdoor unit is not obstructed
  3. Wait for the unit to complete its automatic defrost or warming cycle

Related codes

Pd

Your boiler is stopping itself from working because the water temperature inside is getting too hot, similar to a car engine overheating.

High DIY-safe £100-£350

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate.
  2. Ensure the external magnetic lime-scale filter (if fitted) is not blocked.
  3. Restart the boiler using the reset button to see if the fault clears.

Parts commonly replaced

  • Circulation pump
  • Pressure sensor
  • Thermistor

Related codes

Showing 111–113 of 113
T2

Your heat pump has detected a problem with a temperature sensor inside the outdoor unit, which has caused the system to stop working to protect itself.

High Engineer only £180-320

Parts commonly replaced

  • Plate Heat Exchanger Refrigerant Thermistor (T2)
  • Sensor wiring harness
  • Main PCB
T2B

Your heat pump has stopped working because a sensor that monitors the temperature of the internal cooling liquid has detected a problem or failed.

High Engineer only £180-£350

Parts commonly replaced

  • Refrigerant thermistor
  • NTC sensor
  • Wiring harness connector
Tw_Out

Your heat pump has stopped working because a sensor that measures the temperature of the water leaving the outdoor unit has failed or is disconnected.

High Engineer only £140-£260

Parts commonly replaced

  • Flow Thermistor
  • Sensor Wiring Harness
  • Main Control PCB