Your boiler is struggling to read its own water level because of an electrical sensor issue, which has caused it to stop working as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Water pressure sensor fault
What causes this fault?
This fault occurs when the boiler's internal computer loses communication with the sensor that monitors water pressure. The most common reason is that the sensor has developed an electrical internal short or the wiring connecting it to the main control board has become loose or damaged. Without an accurate pressure reading, the boiler shuts down to prevent itself from firing while potentially dry.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F73 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Ultracom 24cx 30cx is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.