ATAG heat pump faults: fault codes, causes and parts
All 99 fault codes for ATAG heat pumps, plus the faults that show no code. Type your code or choose your symptom.
A fault on an ATAG heat pump usually means that the appliance has locked out or is reporting a fault code. Note the code on the display and look it up below: for each code you will find its meaning, checks you can safely do yourself and the parts that are often checked or replaced. Frequently searched: 937 (no circulation), 2P7 (pre-circulation error), 938 (anode error). No code? Check the power supply, the settings and the filters, and reset once. If the fault comes back, call in a qualified professional.
Most searched ATAG faults
These are the codes that visitors to this site search for most often.
See the 25 most searched fault codes of 2026, with the figures behind them →
ATAG heat pump faults without a code on the display
Not every fault shows a code. These are the symptoms we come across most often with ATAG appliances, with what you can check yourself before calling someone out.
Heat pump no longer produces heat
Check that the system has enough pressure and whether there is a message on the display or in the app. After a power cut, some units start up in a safe mode and have to be released manually. View the matching parts → Read also: heat pump freezes or defrosts constantly →
Outdoor unit freezes or defrosts constantly
A thin layer of ice in frosty weather is normal; the unit defrosts itself periodically. If the ice stays or the unit defrosts every few minutes, the airflow is obstructed or something is wrong with the defrost control. View the matching parts → Read also: heat pump freezes or defrosts constantly →
Too little or too cold hot water
Check the set hot water temperature and whether the electric immersion heater is enabled. A sharp drop in hot water capacity often points to a faulty cylinder sensor or a worn anode in the tank. View the matching parts → Read also: replace the anode before the tank fails →
Noise or vibrations
A noticeably louder noise than normal usually comes from the fan or from vibrations carried through the pipework. Check that the unit stands clear and that the anti-vibration mounts are intact. View the matching parts → Read also: noise and ice on the outdoor unit →
All 99 ATAG heat pump fault codes
Order parts for your ATAG heat pump
ATAG parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
Parts per Atag-series: A Series · i Series (iCon) · Q Series · E Series · P-series (iCon) · Blauwe Engel · XL-series.
Frequently asked questions about ATAG faults
What does a fault on an ATAG heat pump mean?
The appliance is reporting that it has shut itself down or cannot continue. The code on the display points to the group of causes: ignition, water pressure, a sensor, the fan or communication with the thermostat. The table above shows, for each code, what ATAG means by it.
How do I reset my ATAG heat pump?
The reset button is on the control panel of your ATAG heat pump; on most appliances you hold it down for two to five seconds until the display responds. Reset once. If the same fault comes straight back, resetting will not solve it and a part or a setting needs attention. Always consult the manual for your model: the position of the button and how long to press it differ per series.
Can I fix an ATAG fault myself?
You can top up the water pressure, bleed the system, replace filters and clean a siphon yourself. Anything behind the sealed section of a gas appliance is a different matter: work on the gas valve, burner, heat exchanger and flue must be carried out by a certified gas engineer.
How much does it cost to fix a fault?
That depends on the cause and whether a part is needed. With us you can see the part straight away with its price and delivery time, so you know where you stand in advance. If you call in an engineer, always ask about the call-out charge and hourly rate before they come.
Where can I find the right part for my ATAG?
Check the rating plate for the exact type and use it to search our catalogue, or search directly by the manufacturer number of the faulty part. Each part lists the appliances it fits.