Vaillant F72 Fault Code Explained
Hertfordshire, Bedfordshire & Cambridgeshire
An F72 fault on a Vaillant boiler indicates a deviation in the water pressure sensor or the return temperature sensor. Vaillant documentation records it as a fault with those sensors rather than with the water in the system, so the boiler is shutting down because it cannot trust what it is being told.
It is a sensor fault rather than a mechanical one, and it needs an engineer.
What F72 actually means
The boiler relies on its pressure sensor and its temperature sensors to know what the water is doing. If one drifts, disagrees with the others or fails outright, the boiler is effectively flying blind and shuts down rather than firing on bad information. On some models the code points at the water pressure sensor specifically.
What you can safely check yourself
Nothing on this one. There is no homeowner check that helps with F72, and the components involved are inside the appliance. This needs a Gas Safe engineer.
When to stop, and why
There is nothing useful to try. If the boiler locks out on F72 it needs the sensors testing, which requires access inside the appliance.
What causes it beyond the simple checks
A failed water pressure sensor, a failed return temperature sensor, a wiring or connector fault, or occasionally a PCB fault. These sensors are relatively inexpensive parts.
How Vantage can help
We are Gas Safe registered and cover Hertfordshire, Bedfordshire and Cambridgeshire, with an emergency line answered 24 hours a day.
Call us on 01462 506374. See also boiler repair and Vaillant boiler installation.
Frequently asked questions
Is F72 expensive to fix?
Thermistors are among the cheaper components in a boiler.
Can I run the heating meanwhile?
No, the boiler will not fire.
Could it be sludge rather than a sensor?
Sludge causes related codes such as F23 and F83. F72 points more directly at the pressure and temperature sensors themselves.
Related fault codes
Other Vaillant codes: Vaillant F22 · Vaillant F75 · Vaillant F28 · Vaillant F29 · Vaillant F27 · Vaillant F20 · Vaillant F23 · Vaillant F83 · Vaillant F32 · Vaillant F62 · Vaillant F61
See also our guide to boiler not firing up, the full boiler advice section, and boiler repair.
In Vaillant’s own words
Vaillant’s installation and maintenance instructions give F.72 as a deviation in the water pressure sensor or the return temperature sensor.
The water pressure sensor is the part most general advice leaves out. If your engineer is only testing thermistors on an F72, that is worth mentioning.
When to call an engineer
If those checks have not cleared it, the next steps are engineer work and the boiler should not be reset repeatedly in the meantime. Call Vantage Plumbing and Heating on 01462 506374. We are Gas Safe registered under 956889, the line is answered by a person at any hour of any day, and you get a price before anyone starts.
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