Vaillant fault code F.785
Fault code F.785 on a Vaillant heat pump (including flexoTHERM) means: Confirmation signal missing, the fan is rotating. Reset the appliance once. If the code comes back, a part is usually faulty. 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.785 on a Vaillant heat pump indicates: Confirmation signal missing, the fan is rotating.
Applies to
Vaillant flexoTHERM, VWF 117/4, VWF 157/4, VWF 197/4, VWF 57 /4, VWF 87/4.
Fault code F.785 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.785 on Hydraulisch station, 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: Confirmation signal that the fan is rotating is missing.
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 by Vaillant series: ecoTEC plus · ecoTEC pro.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Vaillant sealing ring for e.g. aroTHERM VWL 75/6 A 0020032001 € 9.81
- Vaillant sealing ring 1.1/2" € 15.03
- Vaillant controller cover € 15.68
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.785 mean?
Confirmation signal missing, the fan is rotating.
How do I fix fault code F.785 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.785?
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.785 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 →