Question 1

What does error code F.28 / F.29 u Vaillant and how to fix it?

Accepted Answer

Ignition failure / flame loss during operation. Repair procedure: Closed gas supply valve, faulty ignition/ionization electrode, defective gas valve assembly, or frozen condensate drain pipe.

Question 2

What does error code F.22 u Vaillant and how to fix it?

Accepted Answer

Heating system water pressure too low (below 0.5 bar). Repair procedure: Top up system water pressure to 1.2 – 1.5 bar via the filling loop; if pressure drops repeatedly, check the expansion vessel or safety relief valve.

Question 3

What does error code F.75 u Vaillant and how to fix it?

Accepted Answer

No pressure jump detected when the circulation pump starts. Repair procedure: Clogged/faulty Vaillant water pressure sensor (most common cause!), airlocked system, or seized circulation pump.

Vaillant Fault Codes F.28, F.22, F.75, F.29, F.62 – Error Code Meaning, Troubleshooting & Repair

Error Code Reference Table for Vaillant and step-by-step repair procedure:

Error Code	Meaning / Fault Symptom	Most Common Cause & Repair Procedure
F.28 / F.29	Ignition failure / flame loss during operation	Closed gas supply valve, faulty ignition/ionization electrode, defective gas valve assembly, or frozen condensate drain pipe.
F.22	Heating system water pressure too low (below 0.5 bar)	Top up system water pressure to 1.2 – 1.5 bar via the filling loop; if pressure drops repeatedly, check the expansion vessel or safety relief valve.
F.75	No pressure jump detected when the circulation pump starts	Clogged/faulty Vaillant water pressure sensor (most common cause!), airlocked system, or seized circulation pump.