Ideal Logic+ Heat Fault codes & diagnostics

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

Regular Natural Gas 12-30 kW 2013-present

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Severity at a glance

Each cell = one fault code. Hover to identify.
13 High 1 Low
Just want the most common Ideal Logic+ Heat faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 14 documented codes

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C0

Your boiler's internal computer chip has lost connection or failed to communicate with the main control board, preventing the system from starting.

High DIY-safe £180-350

What to check first

  1. Turn the boiler power off at the fused spur switch
  2. Wait for 30 seconds
  3. Turn the power back on and press the 'Reset' button

Parts commonly replaced

  • Boiler Chip Card (BCC)
  • Printed Circuit Board (PCB)

Related codes

Full explanation for C0
C2

Your boiler's internal memory card has developed a communication fault, meaning the control system cannot verify the specific settings for your model.

High Engineer only £120-£350

Parts commonly replaced

  • Boiler Chip Card (BCC)
  • Printed Circuit Board (PCB)

Related codes

Full explanation for C2
F1

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver braided hose with small valves) underneath the boiler.
  2. Slowly open both taps until you hear water flowing and watch the pressure gauge.
  3. Close both taps tightly once the needle reaches between 1 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure relief valve

Related codes

Full explanation for F1
F2

Your boiler has started to fire up but the flame has gone out, meaning the system has shut down for safety.

High DIY-safe £100-£350

What to check first

  1. Check that your gas supply is turned on at the meter
  2. If you have a prepay meter, check that you have remaining credit
  3. Reset the boiler by pressing the reset button or turning the control knob to 'reset' and back

Parts commonly replaced

  • Flame Sensing Electrode
  • Gas Valve
  • Ignition Lead
  • Printed Circuit Board (PCB)

Related codes

Full explanation for F2
F3

Your boiler has detected an issue with the part that pushes waste gases out of your home, causing the system to shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Venturi tube

Related codes

Full explanation for F3
F4

Your boiler has stopped working because it cannot accurately measure the temperature of the water flowing through the system.

High Engineer only £90-160

Parts commonly replaced

  • Flow Thermistor (NTC Sensor)
  • Wiring Harness

Related codes

Full explanation for F4
F5

Your boiler has lost its ability to monitor the temperature of the water returning from your radiators, often causing it to shut down to prevent damage.

High Engineer only £90-180

Parts commonly replaced

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

Related codes

Full explanation for F5
F6

Your boiler has lost connection with the sensor that monitors the outdoor temperature, which might make your heating less efficient.

Low DIY-safe £90-160

What to check first

  1. Locate the reset button on the boiler control panel
  2. Press and hold the reset button for two seconds
  3. Check if the weather compensation sensor outside looks damaged or blocked by debris

Parts commonly replaced

  • Outdoor weather compensation sensor
  • Wiring loom

Related codes

Full explanation for F6
F7

Your boiler has detected that the electrical supply coming into your home is too low for it to operate safely.

High Engineer only £100-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Voltage Regulator

Related codes

Full explanation for F7
F9

Your boiler’s internal computer brain hasn't been programmed correctly, meaning it doesn't know which model it is and cannot start up.

High Engineer only £100-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • PCB Data Chip

Related codes

Full explanation for F9
L1

Your boiler has become too hot or water is not moving through the system properly, causing the unit to shut down for safety.

High DIY-safe £100-£350

What to check first

  1. Check that your radiator valves are fully open
  2. Ensure your boiler pressure is between 1.0 and 1.5 bar
  3. Bleed your radiators to remove any trapped air

Parts commonly replaced

  • Circulating pump
  • Thermistor (Temperature sensor)
  • Heat exchanger

Related codes

Full explanation for L1
L2

Your boiler has lost its flame while running or failed to light, meaning it has shut down for safety and won't provide heat or hot water.

High DIY-safe £100-350

What to check first

  1. Check that you have credit on your gas meter and that the external gas valve is open.
  2. If it is freezing outside, check if your white plastic condensate pipe is blocked with ice and thaw it with warm water.
  3. Hold the 'Reset' button for three seconds to restart the ignition sequence.

Parts commonly replaced

  • Flame sensing electrode
  • Gas valve
  • Spark generator
  • Condensate trap

Related codes

Full explanation for L2
L5

Your boiler has been manually reset too many times in a short window of time as it tries to clear a persistent underlying fault.

High DIY-safe £0-120

What to check first

  1. Turn the power supply to the boiler off at the fused spur switch
  2. Wait for 30 seconds
  3. Turn the power back on to clear the lockout memory

Parts commonly replaced

  • None (Software reset)
  • Ignition Electrode
  • Flame Sensing Electrode

Related codes

Full explanation for L5
L6

Your boiler thinks a flame is present when it should be off, which is a safety lockout preventing the unit from starting.

High Engineer only £120-350

Parts commonly replaced

  • Flame sensing electrode
  • Printed Circuit Board (PCB)
  • Gas valve

Related codes

Full explanation for L6