- Boilers
- Gas boiler
A05
Cointra A05 on a gas boiler: fan fault, boiler locked out
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Cointra A05 is a fan fault and the boiler locks out. Check from outside that the flue terminal is clear, press reset for one second once and, if A05 repeats, stop resetting and call the technician.
Safety first
Stop and check this first
- If you smell gas: no switches, doorbells or lighters. Ventilate, close the gas tap if it is accessible, leave the property and call the gas emergency line from outside. Cointra says to switch a faulty boiler off and use authorised staff only.
- A fan fault affects how flue gases are removed. If anyone at home has a headache, dizziness or nausea, switch the boiler off, open windows, get everyone out and seek medical help. A CO alarm near the boiler gives early warning.
Safe checks you can perform
- Smell of gas or burning
- Air and flue terminal from outside
- One reset attempt
- Connector, signal and fan by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: 5 pin connector wiring
- Do not attempt this professional task: Actual fan speed
- Do not attempt this professional task: Combustion check after the 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.
5 pin connector wiring
What they doWith a multimeter, the technician checks the 230 V supply to the fan and the continuity of the 5 pin connector wiring, including the tachometer signal.
They must show youthe connector checked and the voltage measured.
In writingthe value measured against the manufacturer's specification and what was repaired.
Actual fan speed
What they doIn the Information menu of Service mode, the technician reads the current fan r/min with the boiler calling for heat.
They must show youthe r/min reading on the display.
In writingthe value read and the conclusion.
Combustion check after the repair
What they doAfter replacing the fan or its wiring, the technician checks CO2 at maximum and minimum output with an analyser and checks the flue.
They must show youthe analyser printout.
In writingthe measured values against the manufacturer's specification and the part replaced with the reason.
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.
Smell of gas or burning
- Who:
- you.
- How:
- without touching switches, check whether there is a smell of gas, flue gases or burnt plastic near the boiler.
- Result that matters:
- whether there is any abnormal smell.
- If it smells of gas or flue gases:
- follow the warnings on this page first.
- If it smells of burning:
- switch the boiler off at its external switch and tell the technician.
- Evidence to keep:
- a note of the smell and the time.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Air and flue terminal from outside
- Who:
- you.
- How:
- from the street, a balcony or a window, look at the boiler flue outlet, without climbing on anything or touching it.
- Result that matters:
- whether ice, a nest, a bag or another object is blocking it.
- If it is blocked:
- tell the technician; Cointra requires the ducts and terminal to be free of blockages.
- If it is clear:
- the likely cause is the fan or its connection.
- Evidence to keep:
- a photo of the terminal.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
One reset attempt
- Who:
- you.
- How:
- press the reset key for one second, the reset method Cointra gives for A letter faults. Do not repeat.
- Result that matters:
- whether you hear the fan start and the boiler works.
- If it starts and A05 does not return:
- note the date; a repeated A05 needs checking.
- If it does not restart:
- the fault is still there and must be repaired; call an authorised technician.
- Evidence to keep:
- a photo of the display and a note of whether the fan could be heard.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Connector, signal and fan by the technician
- Who:
- authorised gas technician.
- How:
- with the power off and gas closed, checks the wiring of the 5 pin connector, the supply and the fan.
- Result that matters:
- whether the supply arrives, whether the speed signal returns and whether the fan responds.
- If the supply is missing or the cable is damaged:
- the wiring is repaired.
- If supply and wiring are fine:
- the fan is confirmed.
- Evidence to keep:
- a report of the checks and the reference of the part replaced.
The fan sits inside the sealed chamber, next to the gas pipe. Cointra says to cut power and gas before touching it: this is work for an authorised technician only.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
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
- Cointra
- Product type
- Gas boiler
Known code variants
- A 05
- A5
- BlueHelix Tech A05
- Cointra A 05
- Error A05 Cointra
- Error A05 Ferroli
- Ferroli A05
- Superlative A05
What it means
In the Superlative Plus fault table, A05 is a fan fault. The fan moves air and flue gases in this room sealed condensing boiler, and the board monitors its speed through a tachometer signal. Cointra gives three causes: no 230 V supply to the fan, tachometer signal interrupted or fan faulty, and says to check the wiring of the 5 pin connector and the fan itself. With an A it is a permanent lockout. The code does not say whether the motor or its connection has failed.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas: no switches, doorbells or lighters. Ventilate, close the gas tap if it is accessible, leave the property and call the gas emergency line from outside. Cointra says to switch a faulty boiler off and use authorised staff only.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Criticaleditorial warning
A fan fault affects how flue gases are removed. If anyone at home has a headache, dizziness or nausea, switch the boiler off, open windows, get everyone out and seek medical help. A CO alarm near the boiler gives early warning.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Symptoms and causes
Probable causes · in order
- No 230 V at the fanPossible
Cointra says to check the wiring of the 5 pin connector. It fits if the fan does not even try to start although the display works.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Tachometer signal interruptedPossible
The board stops receiving the signal that tells it how fast the fan is turning. The fan can spin and A05 can still appear because that signal fails.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Faulty fanPossible
Cointra says to check the fan. It is the cause to confirm when the supply and the signal arrive correctly and the fan does not respond as it should.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Virtual technician
Does A05 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
Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Cointra · 2017 · manual
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