Vaillant fault code F.783
Fault code F.783 on a Vaillant heat pump (including flexoCOMPACT exclusive and flexoTHERM) means: Cable not connected or incorrectly connected. 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.783 on a Vaillant heat pump indicates: Cable not connected or incorrectly connected.
Applies to
Vaillant flexoCOMPACT exclusive, flexoTHERM, VWF 117/4, VWF 118/4, VWF 157/4, VWF 197/4, VWF 57 /4, VWF 87/4, VWF 88/4.
Matching parts
Vaillant parts are available from Instalpunt; shipping to EU countries from €17.95 (€24.95 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.783 mean?
Cable not connected or incorrectly connected.
How do I fix fault code F.783 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.783?
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.783 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 →