BoilerFaultCodes.com

Worcester Bosch Greenstar 25Si Fault Codes

Combi Natural GasLPG 25 kW 2005-2013 Discontinued
GC Number: 47-114-55

Replaced by: Greenstar 25i

This boiler uses indicator light combinations

Note which lights are on, off, or flashing and at what speed. Match the combination to the table below. Do not reset until you have noted the pattern. How to read fault codes →

Most common fault codes

Blue light: Off, Lockout reset: Off
Your boiler has no power reaching it, which means it cannot operate and the display panel will remain completely blank.
May be DIY safe · £80-350
Blue light: On, Lockout reset: Off (Alt 1)
Your boiler thinks it is being told to heat your home even though your thermostat is turned off, usually due to a wiring fault or a stuck control part.
Gas Safe engineer required · £90-180
Blue light: On, Lockout reset: Off (Alt 3)
Your boiler is receiving power but has failed to start up because of an internal electrical or mechanical fault that is preventing it from responding to any requests for heat or hot water.
Gas Safe engineer required · £120-450

All 20 fault codes

Code Severity Plain English
2 pulses, Lockout reset: No light Low Your boiler is not broken; it has simply been left in a manual testing mode and needs to be switched back to its normal setting.
5 pulses, Lockout reset: No light Low Your boiler is currently stuck in a manual testing mode used by engineers and needs to be switched back to its normal operating setting.
Blue light: Off, Lockout reset: Off High Your boiler has no power reaching it, which means it cannot operate and the display panel will remain completely blank.
Blue light: On, Lockout reset: Off Medium Your boiler is providing hot water correctly, but it is failing to respond when you turn your heating on.
Blue light: On, Lockout reset: Off (Alt 1) High Your boiler thinks it is being told to heat your home even though your thermostat is turned off, usually due to a wiring fault or a stuck control part.
Blue light: On, Lockout reset: Off (Alt 2) Medium Your boiler is providing central heating but is failing to detect when you turn on a hot water tap.
Blue light: On, Lockout reset: Off (Alt 3) High Your boiler is receiving power but has failed to start up because of an internal electrical or mechanical fault that is preventing it from responding to any requests for heat or hot water.
E1 High Your boiler has detected an issue with how it clears exhaust fumes, causing it to stop running for safety.
E2 High Your boiler's temperature sensor has failed or has a wiring issue, which means the system cannot safely monitor how hot the water is or provide heating and hot water.
E9 High Your boiler has switched itself off because it is getting too hot inside, usually to prevent internal damage.
EA High Your boiler is failing to light the gas, meaning it has shut down to prevent unburnt gas from building up.
F7 High Your boiler thinks it can see a flame inside the system even though the heating is turned off, causing it to stop working for safety reasons.
FA Emergency Your boiler thinks it still sees a flame even though the gas supply has been turned off, which is a safety conflict.
Fast flash, Lockout reset: Flashing High Your boiler has encountered a critical electronic failure that has caused it to stop working completely as a safety precaution.
Fast flash, Lockout reset: Off High Your boiler has experienced a sudden technical error and has locked itself to prevent damage, requiring a manual reset to attempt to clear the fault.
Over temperature High Your boiler has reached an unsafe temperature and has automatically shut down to prevent damage and ensure your safety.
Slow flash (normally off, flashes on), Lockout reset: Flashing (reset required) High Your boiler has failed to light several times and has locked itself for safety, meaning you have no heating or hot water at the moment.
Slow flash (normally on, flashes off), Lockout reset: Flashing (reset required) Emergency Your boiler has switched itself off for safety because the exhaust gases have reached a temperature that is too high.
Slow flash (normally on, flashes off), Lockout reset: Flashing (reset required) (Alt 1) High Your boiler has shut down because it has detected its internal parts getting too hot, likely due to a lack of water circulation or a blockage.
Slow flash (normally on, flashes off), Lockout reset: Flashing (reset required) (Alt 2) Emergency Your boiler has shut down because it cannot safely expel exhaust fumes, likely due to a blockage in the flue pipe or a buildup of debris.

Worcester Bosch Greenstar 25Si 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.

UK's #1 online installer
Boxt
Fixed-price online quotes. Next-day installation.
Get a free quote →
Heatable
Instant online boiler quotes from £1,499.
Get a free quote →
iHeat
Fast installation. Price match guarantee.
Get a free quote →

Affiliate links — we may earn a commission at no extra cost to you.