AWB fault code F23
Fault code F23 on an AWB boiler (including ThermoElegance) means: Maximum temperature difference between the CH flow pipe and return pipe sensors reached. Reset the appliance once. If the code comes back, a part is usually faulty, often a temperature sensor. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code F23 on an AWB boiler indicates: Maximum temperature difference between the CH flow pipe and return pipe sensors reached.
Applies to
AWB ThermoElegance, 35A, 3 A (N NL), 4 A (N NL) A/2, 4 SOLO A (N NL), 5 A (N NL), 6 A (NNL).
Fault code F23 on other AWB series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- F.23 on ThermoElegance, ThermoGrand, 25A/3, 45S, 65S: Safety shut-down: temperature spread too large.
- F23 on ThermoMaster, CXV 30 A: Water shortage (temperature difference between flow and return sensor too large).
- F23 on ThermoElegance, 3, 4: Water circulation fault.
- F23 on ThermoMaster, CXV 35 A: Water shortage (temperature difference between flow and return sensor too large). Poor contact of flow or return sensor. Flow and return sensors swapped. CH water pressure too low. Pump output too low. Pump defective.
Matching parts
AWB parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
Based on the cause, these original AWB parts fit (always check the type number of your appliance):
- AWB flow/return NTC € 14.37
- AWB O-ring 3 x 13MM 20 pcs for flow sensor € 28.75
- AWB pressure sensor 10 mm € 88.86
Further reading on this cause
Other AWB codes with the same cause
- 06 — Flow NTC fault. NTC is broken or wiring faulty. Check wiring or replace NTC.
- 07 — DHW NTC fault. NTC is broken or wiring faulty. Check wiring or replace NTC.
- 08 — Cylinder NTC fault
- 09 — Water pressure sensor broken or wiring faulty
- 10 — Return NTC
- 19 — Flow NTC fault, dT > 35K 10 times in succession
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does AWB boiler fault code F23 mean?
Maximum temperature difference between the CH flow pipe and return pipe sensors reached.
How do I fix fault code F23 on an AWB boiler?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for AWB fault code F23?
That depends on the exact cause. In the AWB parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code F23 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All AWB boiler faults and codes at a glance →