BoilerFaultCodesYour boiler has detected a sudden drop or change in water pressure and has temporarily paused to re-check the system levels.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Water pressure temporary test.
What causes this fault?
This fault occurs when the boiler's internal sensor detects an abrupt fluctuation or drop in water pressure while the system is running. The most common reason is air trapped in the radiators or a small leak in the system pipework that has caused the pressure to fall below the required operating level.
This fault is more common in autumn when homeowners turn their heating back on for the first time, as air pockets and old leaks often reveal themselves after the system has been sitting idle.
DIY fix possible
Check the pressure gauge on the front of the boilerIf the pressure is below 1 bar, use the filling loop handles underneath the boiler to top it up to 1.5 barTurn the boiler off and back on at the power switch to reset the fault
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 E430 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.