Vaillant [F.32] fault codewhat it means and how to fix it

The fan does two jobs on a condensing boiler: it draws air in for combustion and pushes the products of combustion out through the flue. The control board monitors fan speed continuously through a hall sensor and compares it against what it asked for. F.32 means the two do not match — the fan is running too slow, too fast, or not at all. Because the boiler cannot confirm that flue gases are being cleared properly, it will not allow the burner to fire. This is the correct behaviour and it is why F.32 is not a code to work around. The most common physical cause is simply a fan reaching the end of its life, but a blocked or obstructed flue produces the same reading and carries a different level of risk.

1. 1

   Go outside and look at the flue terminal where it exits the wall. Check nothing has grown across it, no bird has nested in it, and no fence panel, shed or extension has been built near it since the boiler last worked.

   Look, do not poke. Never push anything into a flue terminal — you can dislodge material further in and make a clearable blockage into an expensive one.
2. 2

   Listen to the boiler on startup. A fan that rattles, drones or grinds before locking out is a fan on the way out, and you can tell the engineer that.

3. 3

   Reset once. If F.32 returns immediately or within a few cycles, leave it locked out and book someone.