Vaillant boiler showing F00 or F.00 in Brownhills? It means the flow temperature sensor reading has been lost. What it means and what to do.
F.00 on a Vaillant ecoTEC means the boiler has lost the reading from the flow temperature sensor. Without it, the boiler cannot tell how hot the water is, so it will not run.
Usually the sensor has failed, or its plug has come loose or corroded. Damp can also affect the connection. Your manual will confirm the meaning for your model.
In Norton Canes and Pelsall we see plenty of boilers in garages and utility rooms on the 1960s and 1970s estates. Cold, damp air in those spaces can be hard on electrical connections over a winter.
Switch the boiler off, wait a minute, turn it on and reset once.
Mention if it is in a garage, utility room or loft. Damp spaces make a corroded plug more likely.
The sensor is inside. Testing it needs an engineer.
Tests the flow sensor, cleans or replaces the plug, and checks the reading on the display afterwards.
A photo of F.00, the model from the label, and where the boiler is fitted.
If the boiler lives in a damp garage, a little insulation and keeping the space ventilated helps. Dry air is kinder to plugs and sensors through the winter.
No. The boiler stopped because it lost a temperature reading. Any smell of gas means leaving the house first, leaving switches alone, then calling 0800 111 999 for the National Gas Emergency Service.
Sometimes the plug can be cleaned and reseated. A failed sensor is replaced.
Not necessarily. Sensors can fail on boilers of any age.
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