System pressure has dropped too low for the boiler to run safely.
Most common on: Greenstar 2000 / 4000 / 8000
1017 (shown on numeric-display Greenstar models) means the water pressure in the sealed heating system has fallen below the minimum the boiler needs, typically around 0.5–1 bar.
Low pressure is common and often simple to fix by topping up, but pressure that keeps dropping points to a leak or a failed expansion vessel.
If it reads below 1 bar, the system needs topping up.
Open the filling loop slowly until the gauge reads about 1.0–1.5 bar (cold), then close it and reset the boiler.
If pressure keeps falling, there is a leak or an expansion vessel fault — book an engineer rather than topping up repeatedly.
Work on the gas side of a boiler must be carried out by a Gas Safe registered engineer. The checks above are limited to safe, non-invasive things a homeowner can look at (pressure, resets, the gas supply) — if in doubt, stop and call an engineer.
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System pressure has dropped too low for the boiler to run safely. 1017 (shown on numeric-display Greenstar models) means the water pressure in the sealed heating system has fallen below the minimum the boiler needs, typically around 0.5–1 bar.
Often yes — this one is frequently resolved by a homeowner. If it reads below 1 bar, the system needs topping up. If it keeps coming back, book a Gas Safe registered engineer.
A recurring 1017 means the underlying cause has not been fixed — most often gradual pressure loss over time (normal — needs occasional topping up). Resetting repeatedly will not solve it; get the boiler diagnosed properly.
Pump / circulation fault (dry fire protection)
Overheat — primary temperature too high
See all Worcester Bosch fault codes.