Ideal LOGIC+ HEAT2 Fault codes & diagnostics

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

Gas 2022-present
Choose your boiler type

The LOGIC+ HEAT2 range comes in 5 types

Pick the one you have. The fault codes, GC numbers and manual differ by type.

H12 17 codes · 1 GC number H15 17 codes · 1 GC number H18 17 codes · 1 GC number H24 17 codes · 1 GC number H30 17 codes · 1 GC number
Each model has its own manual A family spans several manuals, one per model or generation. Pick your model above and its page has the manual its fault codes were read from.

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
7 High 2 Medium 1 Low
Just want the most common Ideal LOGIC+ HEAT2 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 10 documented codes

Tap any card for details

4.6

Your boiler's fan, which safely pushes exhaust gases out of the flue, has stopped working correctly and is preventing the boiler from firing up.

High Engineer only £250-450 Shared across the Logic+ HEAT2 range

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
Full explanation for 4.6
4.7

Your boiler detects a flame when it should be off, which is a safety error that prevents the system from starting up.

High Engineer only £180-450 Shared across the Logic+ HEAT2 range

Parts commonly replaced

  • Gas Valve
  • Ionisation Lead
  • Main PCB
Full explanation for 4.7
4.8

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.

High Engineer only £90-160 Shared across the Logic+ HEAT2 range

Parts commonly replaced

  • Flow thermistor (NTC sensor)
  • Wiring harness / connector
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 4.8
4.9

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.

High Engineer only £90-160 Shared across the Logic+ HEAT2 range

Parts commonly replaced

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

Related codes

Full explanation for 4.9
4.10

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.

Low Engineer only £90-180 Shared across the Logic+ HEAT2 range

Parts commonly replaced

  • Outside weather compensation sensor
  • Sensor wiring harness

Related codes

Full explanation for 4.10
4.11

Your boiler is not providing central heating even though it may still be providing hot water.

High DIY-safe £100-250 Shared across the Logic+ HEAT2 range

What to check first

  1. Check that your room thermostat or programmer is set higher than the current room temperature
  2. Ensure the heating mode is active on the boiler display
  3. Check that the radiator valves are open and not turned to zero

Parts commonly replaced

  • External Thermostat
  • Motorised Diverter Valve Head
  • Printed Circuit Board (PCB)
Full explanation for 4.11
4.12

Your boiler is providing central heating as normal, but it is currently unable to heat your hot water.

Medium Engineer only £140-£280 Shared across the Logic+ HEAT2 range

Parts commonly replaced

  • Plate Heat Exchanger
  • Diverter Valve Motor
  • DHW Temperature Sensor
  • Flow Turbine
Full explanation for 4.12
4.13

Your boiler has lost power or the screen has failed, meaning it will not operate and you cannot see any settings or status messages.

High DIY-safe £100-350 Shared across the Logic+ HEAT2 range

What to check first

  1. Check if other appliances in the house are working to rule out a general power cut
  2. Check your home's main fuse box (consumer unit) to see if a circuit has tripped
  3. Ensure the boiler's power switch (usually a fused spur near the unit) is turned on

Parts commonly replaced

  • Display PCB
  • Main Control PCB
  • Internal Fuse
Full explanation for 4.13
Ignition Lockout

Your boiler has tried to start five times but cannot get the flame to stay lit, so it has safely shut itself down.

High Engineer only £120-250 Shared across the Logic+ HEAT2 range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Condensate trap

Related codes

Full explanation for Ignition Lockout
Too Many Restarts

Your boiler has temporarily locked itself for safety because the restart button was pressed too many times in a short period.

Medium DIY-safe Shared across the Logic+ HEAT2 range

What to check first

  1. Wait for 15 minutes to allow the boiler's internal safety timer to automatically reset.
  2. Do not keep pressing the reset button during this waiting period.
  3. Once the 15 minutes have passed, try pressing the reset button once to see if normal operation resumes.
Full explanation for Too Many Restarts
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