Vaillant fault code F.731
Fault code F.731 on a Vaillant heat pump (including geoTHERM 3 kW) means: Refrigerant pressure too high. The integrated high pressure switch has activated at 41.5 bar (g), insufficient energy transfer via the relevant condenser. Reset the appliance once. If the code comes back, a part is usually faulty, often the siphon. 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 F.731 on a Vaillant heat pump indicates: Refrigerant pressure too high. The integrated high pressure switch has activated at 41.5 bar (g), insufficient energy transfer via the relevant condenser.
Applies to
Vaillant geoTHERM 3 kW, VWS 36/4.1 230V.
Fault code F.731 on other Vaillant series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- F.731 on flexoCOMPACT exclusive, flexoTHERM, VWF 117/4, VWF 118/4, VWF 157/4, VWF 197/4: Refrigerant pressure too high. The integrated high pressure switch has activated at 46 bar (g) or 47 bar (abs), insufficient energy transfer via the relevant condenser.
- F.731 on Hydraulisch station, VWZ MEH 97/6 w _ VWL 35_6 A 230V, VWZ MEH 97_6 w _ VWL 105_6 A, VWZ MEH 97_6 w _ VWL 125_6 A, VWZ MEH 97_6 w _ VWL 55_6 A 230V, VWZ MEH 97_6 w _ VWL 65_6 A 230V: Refrigerant pressure too high. The integrated high pressure switch in the outdoor unit has activated at 31.5 bar (g) or 32.5 bar (abs), insufficient energy transfer via the condenser.
- F.731 on aroTHERM split, aroTHERM split uniTOWER, VWL 57 5 IS _ VWL 35 5 AS, VWL 57 5 IS _ VWL 55 5 AS, VWL 58 5 IS _ VWL 35 5 AS, VWL 58 5 IS _ VWL 55 5 AS: Refrigerant pressure too high. The integrated high pressure switch (also replace filter) of the outdoor unit has activated, insufficient energy transfer via the condenser.
- F.731 on aroTHERM split, aroTHERM split uniTOWER, VWL 127 5 IS _ VWL 105 5 AS, VWL 127 5 IS _ VWL 125 5 AS, VWL 128 5 IS _ VWL 105 5 AS, VWL 128 5 IS _ VWL 125 5 AS: Refrigerant pressure too high. The integrated high pressure switch (also replace filter) (also replace filter) of the outdoor unit has activated, insufficient energy transfer via the condenser.
Matching parts
Vaillant 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 Vaillant-series: ecoTEC plus · ecoTEC pro.
Based on the cause, these original Vaillant parts fit (always check the type number of your appliance):
- Vaillant capacitor for e.g. Hybrid Brine Split VWL 35/4 S 230V R1 0020117280 € 54.89
- Vaillant condensate collector for e.g. Hybrid Brine Split VWL 35/4 S 230V R1 0020150137 € 69.26
- Vaillant pipe heating condenser-cooling HEX VWS € 75.79
Further reading on this cause
Other Vaillant codes with the same cause
- F.532 — Isolating valve was not opened, emitter circuit pump defective, all consumers in the…
- F.539 — Amount of refrigerant too low, air flow too low, no defrosting, resistance heater in the…
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 Vaillant heat pump fault code F.731 mean?
Refrigerant pressure too high. The integrated high pressure switch has activated at 41.5 bar (g), insufficient energy transfer via the relevant condenser.
How do I fix fault code F.731 on a Vaillant heat pump?
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 Vaillant fault code F.731?
That depends on the exact cause. In the Vaillant parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code F.731 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 Vaillant heat pump faults and codes at a glance →