- Boilers
- Gas boiler
L5
Ideal L5 on a gas boiler: reset too many times in 15 minutes
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On Ideal boilers, L5 means the boiler has been reset too many times within 15 minutes and has blocked further restarts. Ideal says to turn the power to the boiler off and on again. If the original fault then returns, call Ideal or a Gas Safe engineer.
Safety first
Stop and check this first
- L5 means the boiler has stopped accepting resets: keep pressing it and you only hide the real fault. Power off and on once, then call for help if the original code returns.
- If you suspect a gas leak: put out any naked flame, do not operate electrical switches, open windows and doors, leave the home and call the National Gas Emergency Service on 0800 111 999 from outside, as Ideal's guide gives the number.
Safe checks you can perform
- Code shown before L5
- Power off and on
- Gas supply and condensate pipe
- Diagnosis of the original lockout
Leave these tasks to a qualified professional
- Do not attempt this professional task: Fault history reading
- Do not attempt this professional task: Gas pressure and ignition test
- Do not attempt this professional task: Combustion check after repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Fault history reading
What they doThe engineer reads which lockout triggered the repeated resets and when.
They must show youthe original fault code.
In writingthe fault found behind L5.
Gas pressure and ignition test
What they doIf the underlying code was an ignition lockout, the engineer measures gas pressure at the boiler and checks the ignition and flame sensing circuit.
They must show youthe pressure readings and ignition test.
In writingmeasured values and any part replaced with its reference.
Combustion check after repair
What they doAfter the repair, the engineer measures combustion with a flue gas analyser and checks the flue.
They must show youthe analyser printout.
In writingthe readings.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Code shown before L5
- Who:
- you.
- How:
- remember or note which code appeared before you started resetting.
- Result that matters:
- the original fault.
- If it was an ignition or flame code:
- follow that code's checks (gas supply, meter credit, condensate pipe).
- If you do not know:
- after the power cycle, write down the next code shown.
- Evidence to keep:
- a photo of the earlier code if you have one.
Evidence: Ideal Instinct2 user guide
Power off and on
- Who:
- you.
- How:
- turn the electrical supply to the boiler off at its switch, wait, and turn it back on, as Ideal advises.
- Result that matters:
- whether L5 clears and the boiler tries again.
- If it starts and stays running:
- note the time; watch for the original code.
- If the original code returns:
- stop resetting; contact Ideal or a Gas Safe registered engineer.
- Evidence to keep:
- a note of what the display shows after the power cycle.
Evidence: Ideal Instinct2 user guide · Ideal Heating FAQ: what does my boiler fault code mean?
Gas supply and condensate pipe
- Who:
- you.
- How:
- if the earlier code was an ignition lockout, check other gas appliances, the meter and prepayment credit and look for a frozen condensate pipe at ground level, as Ideal lists for ignition lockout.
- Result that matters:
- whether a simple cause is present.
- If credit was out or the pipe was frozen:
- fix it, then restart once.
- If all is fine:
- the lockout needs an engineer.
- Evidence to keep:
- photos of meter credit and the pipe.
Evidence: Ideal Instinct2 user guide · Ideal Heating FAQ: what does my boiler fault code mean?
Diagnosis of the original lockout
- Who:
- Ideal or a Gas Safe registered engineer.
- How:
- reads the fault history and diagnoses the lockout that triggered L5.
- Result that matters:
- the cause behind the repeated lockout.
- If it is ignition related:
- gas pressure and the ignition circuit are tested.
- If it is something else:
- the code's own checks are followed.
- Evidence to keep:
- a job sheet naming the original fault.
Diagnosing ignition and gas lockouts means working on gas parts; only a Gas Safe registered engineer does it.
Evidence: Ideal Instinct2 user guide
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Ideal Heating
- Product type
- Gas boiler
Known code variants
- aire acondicionado Daikin L5
- climatisation Daikin L5
- climatizzatore Daikin L5
- code erreur L5 Daikin
- codice L5 Daikin
- código L5 Daikin
- Daikin AC L5
- Daikin error L5
- Daikin Fehler L5
- Daikin Fehlercode L5
- Daikin L5
- Ecodan L5
- error L5 Daikin
- errore L5 Daikin
- Ideal boiler L5
- Ideal boiler L5 too many resets
- Ideal L05
- Ideal L5
- Ideal Logic L5
- Klimaanlage Daikin L5
- Mitsubishi Ecodan L5
- Mitsubishi L5 heat pump
- panne L5 Daikin
What it means
Ideal's FAQ describes flashing L and 5 as the boiler having been reset too many times in 15 minutes; the Instinct2 user guide lists the same protection, 5 boiler resets in 15 minutes, under its own code. It is not a fault in a part: it stops repeated restarts while another fault, often an ignition lockout, has not been fixed. The real problem is the code that was being reset before L5 appeared, so that earlier code decides what to check.
Warnings and stop conditions
- Mediumeditorial warning
L5 means the boiler has stopped accepting resets: keep pressing it and you only hide the real fault. Power off and on once, then call for help if the original code returns.
Evidence: Ideal Heating FAQ: what does my boiler fault code mean?
- Criticaleditorial warning
If you suspect a gas leak: put out any naked flame, do not operate electrical switches, open windows and doors, leave the home and call the National Gas Emergency Service on 0800 111 999 from outside, as Ideal's guide gives the number.
Evidence: Ideal Instinct2 user guide · HSE gas safety for homeowners
Symptoms and causes
Probable causes · in order
- An unresolved lockout being reset repeatedlyConfirmed
Fits if another code, such as an ignition or flame code, was showing before L5; the boiler blocks further restarts until power is cycled.
Evidence: Ideal Instinct2 user guide · Ideal Heating FAQ: what does my boiler fault code mean?
- Restarts from a control or timerPossible
Fits if no one pressed reset but the boiler kept trying; an engineer checks why the lockout repeats.
Evidence: Ideal Instinct2 user guide
Virtual technician
Does L5 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Ideal Heating · 2023 · manual
- 2
Health and Safety Executive · official_doc
- 3
Ideal Heating FAQ: what does my boiler fault code mean?
Ideal Heating · official_doc
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