Vaillant fault code F.09

In brief

Fault code F.09 on a Vaillant boiler (including hrSOLIDE) means: Domestic hot water sensor. 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 F.09 on a Vaillant boiler indicates: Domestic hot water sensor.

Applies to

Vaillant hrSOLIDE, VHR 10 S, VHR 18 S, VHR 18-22 C, VHR 24 S, VHR 24-28 C.

Fault code F.09 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.09 on HRV, HRV 24: Water pressure sensor broken or wiring faulty.
F.09 on ecoTEC classic, VHR 18-24/5-3 EXP R6, VHR 18-24/5-3 R6, VHR 23-28/5-3 EXP R6, VHR 23-28/5-3 R6, VHR 28-34/5-3 R6: Short circuit or open circuit of domestic hot water sensor.

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.

For fault code F.09, the part involved is usually in the category: sensor.

Based on the cause, these original Vaillant parts fit (always check the type number of your appliance):

All Vaillant parts →

Other Vaillant codes with the same cause

F.00 — Open circuit of flow temperature sensor
F.01 — Open circuit of return temperature sensor (NTC)
F.02 — Open circuit of DHW outlet sensor
F.03 — Open circuit of cylinder temperature sensor/domestic hot water temperature sensor
F.05 — Open circuit in outdoor temperature sensor
F.06 — Open circuit of inside flue gas sensor

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 boiler fault code F.09 mean?

Domestic hot water sensor.

How do I fix fault code F.09 on a Vaillant 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 Vaillant fault code F.09?

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.09 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 boiler faults and codes at a glance →

Other Vaillant fault codes

Fault code Err Fault code F.00 Fault code F.00 Fault code F.00 Fault code F.00 Fault code F.00 Fault code F.00 Fault code F.01