- Boilers
- Gas boiler
A09
Cointra A09 on a gas boiler: permanent overheat lockout
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Cointra A09 is a permanent lockout from the overheat protection. With the boiler cold, check the pressure gauge: if it reads below 0.8 bar, top up to 1 bar. Then press reset for one second, once.
Safety first
Stop and check this first
- If at any point you smell gas, forget the reset: without touching lights or sockets, open windows, close the gas tap if it is to hand, leave and call your gas company's emergency number from outside. Cointra says to switch a faulty boiler off.
- A09 is a temperature safety cut out. If it returns after a reset with the pressure correct, leave the boiler off. Do not open the casing or handle the pump, sensors or expansion vessel.
Safe checks you can perform
- Pressure gauge when cold
- How the radiators heat up
- Reset once
- Return sensor, circulator and bleeding by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Return sensor reading
- Do not attempt this professional task: Pump, expansion vessel and bleeding
- Do not attempt this professional task: Fault history
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.
Return sensor reading
What they doIn the Information menu, the technician compares the return NTC sensor temperature with the heating sensor temperature and checks the sensor position and connection.
They must show youboth temperatures on the display.
In writingthe value measured against the manufacturer's specification and whether the sensor was replaced.
Pump, expansion vessel and bleeding
What they doThe technician checks that the circulation pump is not seized, reads its speed in the Information menu, checks the expansion vessel charge and bleeds the system.
They must show youthe pump running and the pressure after bleeding.
In writingwhat was wrong and how it was corrected.
Fault history
What they doThe technician reads the last eight faults stored in the History menu to see whether A09 was preceded by F09 or other warnings.
They must show youthe history on the display.
In writingthe codes found.
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.
Pressure gauge when cold
- Who:
- you.
- How:
- wait until the system is cold and read the gauge on the panel. Cointra sets about 1 bar and says to top up if it falls below 0.8 bar.
- Result that matters:
- the pressure read.
- If it reads below 0.8 bar:
- open the filling key anticlockwise up to 1 bar and always close it; the boiler then runs the 300 second Fh purge.
- If it is around 1 bar:
- low water is ruled out as the simple explanation.
- Evidence to keep:
- a photo of the gauge before and after topping up.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
How the radiators heat up
- Who:
- you.
- How:
- during a heating demand before the lockout or after a reset, feel which radiators get warm and listen for gurgling.
- Result that matters:
- whether water seems to be moving through the system.
- If nearly all stay cold:
- tell the technician; it fits with water not circulating.
- If you hear gurgling:
- tell them too; it fits with air in the circuit.
- Evidence to keep:
- a list of cold and warm radiators.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Reset once
- Who:
- you.
- How:
- with the pressure correct, press the reset key for one second, as Cointra explains for A faults.
- Result that matters:
- whether the boiler starts and keeps running without A09.
- If it keeps running:
- note the date and time; if it repeats, it needs checking.
- If it does not start or comes back:
- do not insist; Cointra says the fault must be fixed and the boiler is protecting itself from heat.
- Evidence to keep:
- a photo of the display with A09.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Return sensor, circulator and bleeding by the technician
- Who:
- authorised technician.
- How:
- checks the position and operation of the return sensor, that the pump is not seized, the expansion vessel, and bleeds the air.
- Result that matters:
- whether there was real overheating or the return sensor reads wrongly.
- If the pump is seized or there is air:
- the protection tripped for a reason.
- If the sensor reading does not match the real temperature:
- the sensor is replaced.
- Evidence to keep:
- a report with readings and parts.
Cointra leaves repairs and part replacement to authorised technicians. Return sensor, circulator and expansion vessel are inside the boiler.
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-09
- A9
- Anomalía A09 Ferroli
- Beretta A 09
- Ciao Green A09
- Cointra A 09
- Error A09 Beretta
- Error A09 Cointra
- Error A09 Ferroli
- Ferroli A09
- Ferroli A09 boiler
- Ferroli A09 caldera
- Ferroli error A09
- Superlative A09
What it means
In the Superlative Plus fault table, F09 and A09 are the overheat protection acting; A09 is the version that keeps the boiler locked out until reset is pressed. Unlike A08, Cointra links this code to the return sensor, which measures the water coming back from the radiators. The other two causes are no water circulating in the system or air in it. The code does not make clear whether the water really overheated or the sensor gave a wrong reading.
Warnings and stop conditions
- Criticaleditorial warning
If at any point you smell gas, forget the reset: without touching lights or sockets, open windows, close the gas tap if it is to hand, leave and call your gas company's emergency number from outside. Cointra says to switch a faulty boiler off.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Higheditorial warning
A09 is a temperature safety cut out. If it returns after a reset with the pressure correct, leave the boiler off. Do not open the casing or handle the pump, sensors or expansion vessel.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Symptoms and causes
Probable causes · in order
- Faulty return sensorPossible
Cointra says to check the position and operation of the return sensor and replace it if needed. Suspect it if A09 appears with warm radiators and no noise.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Water not circulatingPossible
Cointra says to check the circulator. If the pump does not move the water, heat stays in the boiler and the protection trips even with a working sensor.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Air in the circuitPossible
Cointra says to bleed air from the system. It is more likely just after topping up or draining a radiator.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Virtual technician
Does A09 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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