Boiler & Appliance Fault Code Finder
Instant diagnostic database of boiler and home appliance error codes. Diagnose Vaillant, Worcester Bosch, Ideal, Baxi.
Water Pressure Sensor / Pump Failure
The boiler fails to detect a 0.2 bar pressure rise when the internal pump starts. Often caused by low system pressure, a blocked pressure sensor orifice, or a worn circulation pump.
1. Check your pressure gauge. If below 1.0 bar, use the filling loop to top up water to 1.5 bar.
2. Press and hold the reset button (flame icon with cross) for 3 seconds.
3. If F75 returns immediately upon heating demand, the pressure sensor or pump capacitor needs replacement.
If water pressure is confirmed at 1.5 bar and resetting does not clear the fault, a certified heating engineer must inspect the pump impeller and electrical continuity.
All Matching Fault Codes
| Brand | Code | Meaning & Cause | Action |
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⚠️ Home Heating & Gas Safety Notice
Homeowners may safely perform external visual checks, clean accessible filters, and top up water pressure using the external filling loop. Never remove a boiler's front room-sealed casing or tamper with internal gas valves or combustion flues. In the UK, internal gas boiler work is strictly legally restricted to Gas Safe registered engineers.
About this tool
How to use it
- Select your boiler or home appliance manufacturer from the dropdown (Vaillant, Worcester Bosch, Ideal, Baxi, Bosch, Samsung).
- Enter your error code into the search box (e.g. F75, EA, F1, E119, E18).
- Review the immediate diagnostic card showing error meaning, severity level, and DIY step-by-step resolution.
- Follow the clear instructions to determine whether a simple pressure top-up/filter clean resolves the issue or if a Gas Safe registered engineer is required.
Why it matters
When a boiler locks out or a washing machine throws an error, calling an emergency engineer often costs £80 to £150 just for a callout fee. Over 40% of boiler lockouts are caused by simple low water pressure or frozen condensate pipes that homeowners can safely resolve in under 5 minutes.
When to use it
Use this tool immediately when your boiler digital display flashes a red light or alphanumeric error code, or when your washing machine halts mid-cycle with water in the drum.
Good to know
Includes safety boundary guidance. In the UK, internal gas work is strictly restricted to Gas Safe registered technicians. Homeowners may safely repressurise boilers and clear exterior pipes.
Common questions
What should my boiler pressure gauge read?
When the heating system is cold, the pressure gauge should sit between 1.0 and 1.5 bar. If it falls below 0.8 bar, most modern combi boilers shut down with an error code.
Can I legally repair my own gas boiler in the UK?
You can safely repressurise the system using the external filling loop, thaw an external plastic condensate pipe, and reset the unit. However, removing the front casing or working on gas components is strictly restricted by law to Gas Safe registered engineers.
Why does my Vaillant boiler show F75?
F75 signifies that the boiler pump started, but the pressure sensor failed to detect the required 0.2 bar pressure rise. It is typically caused by low system pressure, a clogged sensor, or a failing pump.
What causes washing machine error E18 on Bosch machines?
Error E18 means the drain pump filter is clogged or the drain hose is obstructed. Emptying trapped water and cleaning coins or hair from the bottom pump filter will almost always resolve it.